NATURALISTS’ FIELD CLUB

Otago Daily Times, Issue 18540, 28 April 1922, Page 8

NATURALISTS’ FIELD CLUB

“ SOME ANCESTORS OF THE OCTOPUS.” The indoor meeting of the Field Club, held on Monday evening, proved intensely interesting to the members. Hr "Williams (vice-president) was in the chair. Mr ri. Finlay read a paper entitled “Some Ancestors of the Octopus,” in which wan traced the gradual rise of these animals from their earliest known forms. The paper mentioned that in the earliest fossil-bearing rocks unmistakable evidence was found that the shell fish were even then well developed, but that the only representatives of the Cefhalofods, or “arm-footed” animals, the class to which (ho octopus belongs, were certain primitive straight-shelled forms allied to the Nautilus of (he present day. These soon gave way to the Ammonites, a curious class of shells whose members were now wholly extinct. They were at first a very actively-growing race of great vital power and evolutionary susceptibility, but probably through attempting too much, and exercising their powers of change to excess, they exhausted the race, as well as their individual selves, and all finally perished. The paper then dealt with the rise of a new stock—the Belemnitca, or “thunder-holt fossils,” and the various branches that evolved from them. These animals, which must have looked very much like cuttle-fish, hut had a much larger internal skeleton, tended (o give up a sluggish life on (lie sea floor and take to the _ open ocean. This necessitated greater activity and intelligence; there was then leas need for the protective shelly skeleton, which was thus gradually reduced, till most of the modern squids possessed only the long thin “fen.” One of the descendants of these forms which had retained a coiled and chambsred shell was Spirilla; whose shell was cast in thousands on New Zealand shores, though the animal was very rare indeed. The paper closed with an account of the modifications of the cuttle-fish structure that had led to the rise and development of the octopus. The 10 arms had been reduced to eight, all of equal size, together with changes of tl.e fins and loss of the internal shell. The order to which the octupus belonged was at its maximum at the present clav, and contained the highest number of backbonelcss anima's. A lengthy and keen discussion followed, Mr Finlay being congratulated on tho clear and lucid manner in which he had treated his subject. Two new members were elected, and a opmmittee was appointed to select a design for the club badge. Miss Cartwright brought forward a specimen cf fungi. Miss Scott exhibited a specimen of Rhyssa antipodum. and some beetles collected at Stewart Island. Owing to Saturday’s boisterous weather, the work of recording tho natural history of tho Otago Peninsula was again interrupted, the excursion arranged for Tomahawk, via Highcliff rocks, being postponed.