Discovery reports (1937) Discovery reports discoveryreports14inst Year: 1937 246 DISCOVERY REPORTS One of the strongest differences between them is that E. spmifera has hepatic spines while E. longirostris has not. It is surely significant that E. hanseni should have hepatic spines like E. spinifera and that E. triacantha should, like E. longirostris, have none, but that both should have a mound-like projection on the carapace similar to that from which the spines arise in the other two. It is significant too that it is an end member of the series that differs most from all the others—that i
Discovery reports (1937) Discovery reports discoveryreports14inst Year: 1937 246 DISCOVERY REPORTS One of the strongest differences between them is that E. spmifera has hepatic spines while E. longirostris has not. It is surely significant that E. hanseni should have hepatic spines like E. spinifera and that E. triacantha should, like E. longirostris, have none, but that both should have a mound-like projection on the carapace similar to that from which the spines arise in the other two. It is significant too that it is an end member of the series that differs most from all the others—that it is E. triacantha that has no post- ocular spines and a copulatory organ most unlike those of the other three. In the cha- racter of the structures on the second segment of the antennular peduncle there is an appearance of a progression or trend which corresponds with the order of occurrence of the species. THE SOUTHERN GROUP My second natural group, which I shall call the Southern Group, comprises E. liicens, E. vallentini, E. frigida, E. siiperba and E. crystallorophias and has not before been in < X Q. a cC q z -I _j < p < ca - Q. _l a: 3 E LJ ui LJ 1 l/l u 13 Ul SUB-TROPICAL CONVERGENCE ANTARCTIC CONVERGENCE - EDGE OF PACK-ICE ANTARCTIC COAST-LINE o OL , <liJ HZ ZO <N m 10 LJ z o N o a: < I- z < Fig. 29. Diagram showing the distribution of the species of the southern group of Eiiphaiisia in the surface zones of water in the southern oceans; the blacked in portion of each column shows the normal range of that species, the entire column the possible range. recognized as such; E. vallentini comes from Hansen's Group c, the other four from Group b. They share no obvious external characters, such as the abdominal spines of Group d, to make them look like related species. I find the relationship to be shown by the structure of the male copulatory organs, especially by that of the proximal process.
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