60 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



the out-stretched appendages. Although not, of course, a 

 discovery in Marine Biology, it may be noted here that Moseley 

 was enabled, by the examination of fresh specimens of Peripatus 

 obtained at the Cape, to demonstrate the essentially Tracheate 

 nature of that primitive and annectant form. Living repre- 

 sentatives of the fossil Trilobites were eagerly looked for — 

 but never found. 



In the Mollusca, as in Crustacea, we find a tendency for 

 the eyes to degenerate or disappear, in deep water. The 

 " Challenger " collections enabled Pelseneer to establish 

 a phylogenetic classification of the Larnellibranchiata based 

 on the structure of the gills, and to show that the pelagic 

 Pteropods are a polyphyletic group, some of which are related 

 to one, and the rest to another, section of the Opisthobranchiata. 

 One of the prizes obtained was the living specimens of Trigonia, 

 dredged off the coast of Australia, a primitive cockle-like 

 form found fossil in European rocks of secondary age, and 

 long supposed to be extinct. 



In the Cephalopoda the single specimen of Spirula, of 

 which only five individuals are known to science, is one of the 

 priceless treasures of the expedition. A living Nautilus 

 pompilius was brought up from 320 fathoms, off Fiji, and 

 Moseley has given us a description of its swimming movements 

 in a tub of water on deck. It had been confidently hoped 

 that some deep-sea representatives of those extinct groups, 

 the Ammonites and Belemnites of Mesozoic times, would 

 be found, and Moseley tells us that " even to the last every 

 cuttle-fish which came up in our deep-sea net was squeezed 

 to see if it had a Belemnite's bone in its back " — all in vain — 

 no such " living fossil ,? was found. 



One of the greatest discoveries of the " Challenger " expedi- 

 tion was the remarkable Cephalodiscus, dredged in the Straits of 

 Magellan from 245 fathoms. It is a gregarious member of the 

 Hemichordata related to Rhabdopleura and Balanoglossus, 



