NATURE NOTES.

New Zealand Herald, Volume L, Issue 15252, 15 March 1913, Page 5 (Supplement)

NATURE NOTES.

BY J. DRUMMOND, V.L.8., F.Z.S. Mr. "C. HuTCHinrs,' of Omokoroa, ,T«w ranga, states that he has been puzzled for many years in regard, to the origin of cigar-shaped objects which are thickly strewn over arable-land-in;-Essex, England, and. which the rural inhabitants of ; . that "country call thunderbolts. * From aT ' rough sketch of one of thesethunder--bolts, I have no difficulty in identifying them as belemriites. They are a race of creatures which disappeared ' from the world tens of thousands of years .ago. f. - The "perfectly round,- creamy-yellow tinted things," to use Mr. Hutchins'B words, are the fossilised skeletons of animals which belonged to the cuttlefish group of molluscs. The fossils are conical in shape, tapering to a point at the lower extremity. At the thick-end, usually, they are broken, but, when perfect, • that end contains a small chambered cone. ..; The length of one of these fossils sometimes reaches over three inches. •It is chiefly the hard parts of the animals that '' : have been preserved, but some specimens r show that the belemnite had the typical structure of the cuttlefish. In the flesh, -. the body was tapering; there were side ; fins eight arms, furnished with horny hooks and tentacles; and probably there „ 'we're horny mandibles at the mouth. In. . the last chamber of the chambered cone there was an ink-bag, which is frequently found in a well-preserved condition. The belemnites appear first in the "Tipper. Trias v system of rocks, which are far down in the geological succession, iln the Jurassic : Period, which follows the Triassic, they ' advanced rapidly in numbers, and also- in variety of/ form, a fairly large number of 1 species having, been identified. ... In. the i . Cretaceous Period, which follows' the Jurassic in geological succession, they : were, very abundant in the northern seas. Apparently, they are specially well"'.re- "'' presented, in the Seeton -Beds, a series of-* clays largely exposed at Seeton, near Filey, on the . coast of Yorkshire, England. They lived in New Zealand seas, and Mr. R, Speight, lecturer on geology at Canterbury College, tells me that their . fossil remains, similar .'in appearance to .< those'that excited Mr. Hutchins's curio- V sity, "are found in : ; large numbers at ~'l the Aniuri Bluff, in North ..'Canterbury, 1 and at Kawhia, on the West Coast of the ■- North Island. f-Mr.-Hutchinß "has - asked",: me to write something about the " Devil's ■■*• Toenails," also found in.Essex. He says•■"_" that they are like • '* seedy;*'<lißeased - toes* ';■'.. "nail's, of a dark slate colour, and, when " . broken up, part into flakes like an oyster •- - shell."- They are an inch long and "half •; .an' inch broad, and from'three-eighths -ofc ~ 'an- inch to a ■quarter of "an inch thick?'"* These, also, -apparently, are some kind 1 J of y fossil, but it is difficult ■ to ' identify ". them from the description!- It has been**-"' suggested to me, however,-that they are-:• aptyclius, a shelly glate found .ni the last; " chamber of Ammonites. "; .••--;:..,i-•; : Ammonites, also, lived in"New Zealand ?- seas' in- ages that are;separated from-the.?'; present by a vast gap -of; time.' In NewVtv. Zealand- rocks they are" found .in";a con-: •' 3' dition that approaches fairly closely to perfection. The ammonite has a peculiar .1 fascination to human inhabitants.- of the;;" -v earth, first because of its mysterious and ;: unaccountable extinction, ana also because... it closely resembled our own k chambered, , nautilus, whose delicate■■'•.-beauty OliverWendell Holmes 'described-in - his poem. iJHolmes's lines, indeed, when applied -to.-.»>;■ the : mighty hosts of i ammonites which, . have been dismissed from the universe, strike a much deeper note than when they — are applied to the .single "child of the wandering sea'-. he picked up on.th©, 4/ American shore: •..■"■;. Its web 'of-living gauze nd' ; more un'turjs*' ; , ['"_■ '■' Wrecked 'is the ship bf^iearl!..•-"•'.■ •-'■/ ••" And "every chambered cell, ;"- ■-..". i.S'Where, its dim dreaming life was wont to dwell, As the frail tenant shaped' hi» -Krowipg; shell," . -; Before thee: lies revealed '* ■ - ■ '■■--'■ -A Its irised ceiling rerit, its sunless crypt unsealed! '" ' '-'■ The shell of the ammonite, like that of ■■ the . nautilus.. was .spiral, and chambered.- - •'• The: mollusc-.owner, apparently, .lived in- '■■• the last and largest 1' chamber. ' Several.- ■• hundred- pi dossil . ; ;,.wn?„ ; r - monites have been identified.: These show', astonishing differences in size. Some are so minute that they are smaller • than "- •- buttons; some are several inches in.; dia- ?r .;- meter •: and y some are as ; large .as cart^ ■ wheels. Small and medium specimens arev found In New Zealand..,. In the-British. , Museum l&ere is a■■, specimen;.-found at ', Eottingdean, > near ..-' Brighton, - England, 3 • three- feet eight inches in. diameter. ; The" : largest specimen known came from West-' iphfiia,'-Germany <- fits stupendous dimen*',^ " ';siohs;,are;; represented !by its diameter,,^■; : which is ho less Jban six ; feet eight ~ . inches. The differences in the . am-.-: . monite's size are" hardly less surprising;. . than 'the differences in shape. The earliest ammonites were straight. As the 1 vast :■ ages passed, a coil became fashionable, '"': and the, shell finally took the spiral form* . now affected by the nautilus... The ispirai „, was ': maintained throughout the Mesozoic ]_ or Secondary Age. Towards the end of " that age, when the race .was threatened: ' " with the fate of extinction, an effort, eyi-'; '■) ' ', dently, was made to take' on the driiginal -.?;.■ form. Some species succeeded, but others, , before finally disappearing, as a . paiaa-' . ontologist . has graphically described' it. ~ , r " twisted and untwisted themselves,' arid',"-.'; wriggled themselves into ' extraordinary' ; shapes, in the last throes of dissolution;-5 Trilobites. are another race; or creatures'; whose fate it has been to be swept Out of ;■; existence. Although they resembled the ' ; . wood-lice of the present time, to .whicb.'. they were fairly closely related,; they were" ' purely aquatic animals. - ; They L swarmed in countless numbers in ancient seas,; here •: and other parts of. the world, but in- : "' i ' stead of living an active life in the open / water they were content to crawL along •' the mud and sand-at the bottom and feed " upon worms and other " small cfeer."s;' { When danger threatened: ; them they; burrowed beneath 'the surface of the mud '■'■'• As another means of ' defence against enemies, every trilobito could toll itself * up into a ball, bringing its tail into con- r* tact with its head. A marked difference - ; in structure has been found in the differ*' * ' ent species, but all are characterised by a* >■-■. head-shield or buckler. This usually is a,-"' semi-circular shape.: 1 ' In all species except • -';■' ' a few ; that are , blind, the shield l bore .* ~ pair of large, kidney-shaped a compountt.. eyes, like those of the king-crab. There-• was also a tail-shield, which in-some cases- ' was as large >as.the<beadfshield. "■ -1-. At one-' time scientists, hoped that extensive » '• dredging operations. on the floor of..the,.;: '- ■ ocean; would reveal the presence. of living;. ,-■ trilobites. When the Challenger expedi v . tion came to these seas, years; ago,- iit was , believer that these hopes would- b«i real-v----ised, but the operations: resulted, iia dis» ; appointment,,. as . far -as obtaining living v trilobites is concerned..;:, ~ Both ammonites and trilobites; play an :. •- important part in theories dealing- with « • evolution and the origin ,of life. . Darwin,".',>; taking these. two extinct races.as ill ustra* i. . tions, argue 1 that the manner in which! ~ ' single species of animals and whole groups ' of species had become extinct agree«l well y; •with his theory of natural selection.: He- - •'■'■ did not try,to unravel the deep mystery, iy of the ammonites' and trilobites* extinction. "We need not marvel at these extinctions," he'said; "if we must marvel, - :■ ■■ let it be at our presumption in imagining for a moment that ;we understand- , the ; many complex contingencies on which the existence of each species depends.'" The . life-history of the trilobites is exception* ~.• ally, puzzling. , There is absolute ignoir '. ance m regard, to. either their origin. o*'. the causes that brought about their awful fate. They appear . back in.- the » Cambrian Period. This immediately, ceeds'. the Archean, in which no,forms of . life have been traced,; and .the;? rsr* amongst the earliest known fossils. Even, then, when, , according to the geoiiogical...:; records the world was young indeed,' they,., ■ had reached a high "standard of structure.; „ The theory of, evolution provides that they ", must have been preceded by much simpler types, and this lino of reasoning, <ei&.0B«~ 5 investigator • has said, refers ; the-" origin >. of life back to a time: immeasurably, da-- > r ' tant from the earliest date at' which we ': I know, as a matter of actual ; proof,,; the* and plants Uvv*