IN TOUCH WITH NATURE

Otago Witness, Issue 3714, 19 May 1925, Page 6

IN TOUCH WITH NATURE

NEW ZEALAND SHELLS.

(By

J. Drummond, F.L.S.. F.Z.S.)

A visitor to Takapuna, near Auckland, has sent several fairly large ribbed bivalve shells he picked up on the beach there, and has described them as scallops. Thev are not scollops, but large dog-cockles, or comb-shells. A comparison with description* and plates in Dr C. E. R. Buoknill’s book on New Zealand shells shows that they are, conchologioally—-malcologically, to use a newer term--Glycymeris luticostata. Dr Bucknill makes everything easy for readers of his popular book. Following his translation, tho title means the bitter-sweet, vvido-ribbed shell. It is found on many New Zealand coasts, in shallow water, and it has left a fossil record in the rocks of the world. As far as its dimly-written history it came into the scheme of creation in the Cretaceous Period, which was at the end of the Mesozoic or Secondary Era of life. In the Carnozoic or Tertiary Era, which followed, it had spread widely over tho world. In these postTertiary or recant days it is found in the teas of New Zealand, Australia, India, Western America, the West Indies, and tho United Kingdom. Its earliest record in Now Zealand is in Senonian times, at the end of the Cretaceous Period. WhiJo tho larger and the lesser dogcocklo arc common in New Zealand this dominion also has Its scallops. Its own particular scallop, Pecton Zelnndi*. is described by Dr Buckniy as tho ino»t beautiful of all the scallops. It seems to be known better os the fen-shell, on account of its shape. In colour, he states, it may be red. brown, orange, canary yellow, or

purple, and sometimes varied .with puce and purple. Rocks and loose boulders and the roots of seaweeds and sponges are the places in which to look for it. The scallop shell worn by palmers who returned from the Holy Land, one of the historical shells of the world, is suggested in New Zealand bv a somewhat small bearded scallop which attaches itself to rocks and boulders iust below low-water mark. A large scallop found in New Zealand, Pecten medius, has splendid eyesight. Its eyes afte tiny black spots on the outer border of its mantel. Dr Bucknill has watched it snap its valves together when it i 9 approached. 110 has found substantial qualities in this large scallop, sometimes 6in across. “It is an excellent shell fish for the table, ranking second to only ♦he oyster of the Old Country, but in New Zealand it is hardly known of as foqd. The Maoris seldom used it in that way, and its remains seldom seen in old iniddens. The only reason for the neglect is that generally it has to be dredged for in deep water.” Tho dominion’s shells, like its insects, birds, and alpine flowers, usually are more sombre than those of some countries. One of its most beautiful shells is one of its rarest. This is Ampullina undnlato, a globular shell about nn inch in diamotoi. ihe following ig Dr Bucknill’s description of it:—‘‘Pure snow white, very often fragile, pellucid, sculptured with only tho faintest of growth lines, crossod by delicate spiral striations. The simplicity of design and the subdued schome of decoration, instead of detracting from its charming appearwioe, rather add to it.” Mr H. outer, In hit book on Now Zealand molluscs, states that he did not see this gem of the shells. Fortune smiled on Dr Bucknill one morning when he stooped to pick up an empty shell in excellent condition, washed up on

the beach at Mount Maunganui, neai xauranga. Some entomologists seem to believe that wetas are harmless. . These large, longlegged, grotesque insects, with skins like polished or marbled wood and the appearance of monstrous fleas, are plentiful in New Zealand, but different species have different habitats. Most of them are sufficiently formidable as far as their looks go to cause suspicion, if not some degree of dread. The smaller species may he harmless, but a large specimen, whose striped body is an inch long, head a-quarter of an inch long, and legs about an inch and a-quarter long, and whose head is surmounted by two straight antennre that stand out like horns, amply justified any ill-will towards it. Mr H. P. Savoy, Main road. Lower Hutt, Wellington province, who sent it, states that it made a savage attrack on his finger when he was gardening on the front of a rockery. A fairly large number of the. wetas are cave-dwellers, some are forest dwellers, and some, apparently, adapt themselves to almost any environment. The koromiko and other New Zealand veronicas evidentjy have a particular attraction for a shiny black and very small fly whose grub makes long, narrow galleries in the leaves of those plants. This insect has come under the notice and, to some extent, under the microscope, of Mr M. N. Watt, the .only entomologist who is studying leaf-mining insocts in New Zealand. His observations show that the adult female veronico fly lays her eggs in smnll pockets in the leaves. The egg-pockets soon become discoloured, dark brown or black, and then are very conspicuous. Homo of the pookets made by a female do not oontain eggs; they are made for refreshment only, tho female eagerly tucking the exuding sap from the

puncture. Usually there is only one gallery on each leaf, but a large leaf may have two or three galleries. The grub, when full grown, emerges from the gallery it has made, making a semi-circular cut in the epidermis of the leaf at the end of the gallery. In almost every case, escape from the prison is made through the roof of the gallery. After escape, the grub descends to the ground, to advance a step in life by becoming a chrysalis. In Mr Watts’s "breeding jars, grubs never went beneath the surface of the sand for this important change. The pale, ambercoloured chrysalis sleeps for from about 25 days to atxmt 40 days before the greatest event of the fly’s life takes place—namely, its emergence as a perfect insect, perhaps only an eighth of an inch long, but equipped in every particular for life amongst the flowers. Leaves of the brilliant crimson kowhai are industriously mined by the grub of a sober-coloured fly about half the size of the koromiko fly. The large-flowered clematis, pikiarero, is attacked by the grub of a slightly larger fly. This insect makes a tortuous, narrow gallery. Tho alpine bush flax is used in the same way by tho caterpillar of one of New Zealand’s most beautiful moths. The caterpillar becomes a chrysalis in a cocoon. There it stays for six or seven months, while it is slowly undergoing the mysterious metamorphosis that ends In a metallic purple-bronze moth, with pale lemon yellow markings. The change tokeß place In the cocoon, and the moth forces its w ay out of the iroper end where the outer covering is only lightly secured. Mr J. Young, of Opunae, Auckland province. saw & small shoot growing out of a holo sft deep in a makaumabnn tree. He was sufficiently interested in the growth to cut the tree down and split the part

that contained the shoot. He wa9 surprised tp find that it was a vegetable caterpillar. ‘‘l had thought that these fungi always were found on the ground,” he writes. Ho asks how long it takes for the fungi to transform the caterpillars into vegetable substance, but there seems to bo no record of this. The time, probably, varies in tho individuals attacked. A list of birds and other animals, prepared by children at the Romahapa School, Otago, shows that native birds in that picturesque -district are holding their own. Tuis and bellbirds come about the trees and into the school garden, and feed on yellow kowhais which grow close by. Tho native and introduced fuchsias and flowering currants, flax, and Laurestinus also aro favoured by the birds. Bellbirds sometimes feed on a Laurestinus bodge while children stand close by and watch them. Tt is satisfactory to note that a few parrakeets, which have sadly diminished in numbers during the past 20 years, came near the school last summer. In the list of some 35 native and introduced birds are the morepork, owl, and the little grey owl, or German owl, tho robin, the prey warbler, the tomtit, tho wren, the kaka. the kood-pigecn, the longtailed cuckoo, the ground lark, the penguin, the dotterel, the kingfisher, the albatross (on the coast), the muttonbird, the waxeye, the fantail, the useful little hedge-sparrow, in no way related to its better-known namesake, the redpoll, one of the most useful, as well as one of tho prettiest, birds introduced to this dominion, the gaily-dressed goldfinch, the quail, and the black swan. Amongst the wild mammals are rabbits, hares, weasels, stoats, hedgehogs, opossums, and nigs. Reptiles are represented bv three species of lizards, all natives. Romahapa is eight miles south of Balclutha, on the Catlins branch line of railway. The school is about only four miles from the coast. It stands on a hill about 300 ft above sealevel. A range of hills lists to the south and the west, and there are remnants of a great forest which began there and stretched for GO miles through the Catlins district towards Fortrose. On tho western side of the Clyde River, South Canterbury, there is a series of hanging valleys described by Professor It. Speight, of Christchurch, a 3 “so perfect in. arrangement and features that they might almost be sketches in a text-book.” Hanging valleys, which seem to overhang ordinary valleys, are the result of action by glaciers. In the Lawrence Valley, in the same district, Professor Speight saw the remains of glaciation in their most perfect form. He states that “old moraines, forming complete dams across the valley, except where breached by the river,-lateral moraines, spurs, and other evidence of the action of glaciers, occur almost 33 fresh as if they had been formed yesterday. “The only remnant of those old glaciers is a small valley-glacier, about a mile long, at the head of the Lawrence River, and small cliff and corrie glaciers' on the south-eastern slopes of the Jollie Range. These glaciers now occupy the upper parts of the hangingvalley basins excavated at the time of tho old ice-flood.