CRUSTACEA MALACOSTRACA. III. 



cally, and referred besides to the gatherings of the "Thor" in the Mediterranean and the adjacent parts 

 of the Atlantic. In his later report (1915) on these gatherings we find the following lines |p. 26): 

 "H. J. Hansen mentions, among the Tanaidacea of the Ingolf Expedition . . . certain species, the occur- 

 rence of which is contrary to zoogeographical laws, inasmuch as they appear to belong both to the 

 boreal southern and northern arctic ocean deeps off the coast of Greenland". And later: "Dr. H. J. 

 Hansen however, maintains that all Tanaidacea belong to the bottom fauna, despite the fact that the 

 occurrence of the "doubtful" species is very easily explained if they are taken pelagically". 



Stephensen's expression: "contrary to zoogeographical laws" is a little too strong, as according 

 to Th. Mortensen a few Echinodermata do not obey the "law"; the term "rule" would have been 

 better, as rules generally are not without exceptions. He is quite right in saying that "the occurrence 

 of the "doubtful" species is very easily explained if they are taken pelagically", but this explanation is 

 only a hypothesis, and we must now examine the foundations for this assumption. All his statements 

 on specimens of the order Tanaidacea shall be taken into account, while his utterances on Cumacea, 

 on a couple of Gammaridea, etc. are discarded as being without the slightest value as to conclusions 

 on Tanaidacea and Isopoda. 



In his last-named paper Stephensen enumerated 16 specimens belonging to 3 species of Apscudcs 

 as taken all at the same place in young-fish trawl with 25 m. wire out, while the depth of the sea was 

 600—620 m. The statement is valuable in showing that animals of the family Apseudidse in reality 

 can swim about rather near the surface in a sea of considerable depth. But according to kind infor- 

 mation from Dr. Job. Schmidt the locality in question is situated, between Corsica and Elba, about 

 18 sea-miles from the former, 16 sea-miles from the latter island, and only 5 — 6 sea-miles from the 

 flat with the depth of 200 m. off Elba. The only other case recorded in the literature of a form of 

 the Apseudida; having been taken pelagically is found in my report on the Isopoda etc. of the German 

 Plankton-Expedition, where I said (p. 49) that a single very young specimen of Apseudes had been 

 taken in the Gulf of Guinea at St. Thome. Now it must be emphasized that both females and males 

 of the family have their pleopods, judging from their appearance, rather well developed for rowing, 

 though not for vigorous movements, and the two above-named gatherings show that animals of the 

 family have been taken, at least at night, swimming about at a proportionately moderate distance 

 from two islands and not very far from a flat. Otherwise these two instances prove next to nothing. 

 Dr. Joh. Schmidt has hundreds of times used by day, or at evening or night, the young-fish trawl in 

 various depths without coming near the bottom; in this way he explored the seas at Iceland, at the 

 Faeroes, and further south in the Atlantic to Morocco and the entire Mediterranean; he never caught 

 a specimen of Apseudidse very far from any coast, and in reality only the single case mentioned, but 

 animals of the genera Apseudes and Sphyrapus are so large that they must have been captured among 

 the enormous quantities of Copepoda and other small Crustacea, and are easily discovered in the 

 samples. Furthermore a rather good number of species of Apseudes, taken in dredge or trawl at the 

 bottom, are known from the seas explored by Dr. Joh. Schmidt. The explorations of Dr. Schmidt 

 together with the fact that the German Plankton-Expedition did not take one single specimen 

 of the whole order in its very numerous vertical hauls in most different depths show 

 with sufficient clearness that animals of the family Apseudidse do not live pelagically in such a way 



