66 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I28 



Podocerus latipes Boeck, 1876, p. 600, pi. 29, fig. i. — Hansen, 1887a, p. 161, 



pi. 6, fig. 3. 

 Podocerus assimilis Sars, 1885, p. 205, pi. 17, fig. 1. 

 Ischyrocerus assimilis -\- latipes Stebbing, 1906, pp. 659, 660. 

 Ischyrocerus assimilis Stephensen, 1944a, p. 31, figs. 22, 23. 



Material collected. — In depths from the beach down to 520 feet, 

 between July 21, 1948, to July 29, 1951, about 300 specimens. 



There are reasons that lead one to believe that Ischyrocerus latipes 

 Kroyer and Podocerus assimilis Sars are one and the same species. 

 Kroyer did not give the length of /. latipes, but Stebbing gives the 

 length as 14 to 15 mm. Podocerus assimilis was described from a 

 small specimen of 8 mm. The discrepancies in the descriptions of 

 these two species could be due to the immaturity of Podocerus 

 assimilis. Sars shows the lower hind corner of the third metasome 

 segment as evenly and broadly rounding, which may have been due 

 to the difficulty of observing the outline of the colorless transparent 

 segment. In larger, more-mature specimens, this angle is quadrate 

 or even slightly produced. He figures the first and second uropods 

 as having very few spinules, which is correct for small specimens 

 where the spinules are few and difficult to observe. The number of 

 spinules on the uropods increases considerably with the size of the 

 animal. In the specimen of assimilis measuring 9 mm., figured by 

 Stephensen (1944a, p. 31, fig. 22u), there are 10 spinules on the 

 outer margins of the outer ramus of the first uropod, while in speci- 

 mens from Point Barrow measuring 16 mm. there are at least twice 

 that number. The specimens from Point Barrow that have been identi- 

 fied as Ischyrocerus latipes agree with the figures given by Stephensen 

 for Ischyrocerus assimilis. Little can be learned from Boeck's figure 

 (1876, pi. 29, fig. I ) which, if it is of /. latipes, does not agree in some 

 characters with that species. The specimens from Point Barrow and 

 Stephensen's figure of /. assimilis agree with the figures given by Han- 

 sen (1887a, pi. 6, fig. 3) of Podocerus latipes as far as they go. 



This species was correctly placed in the genus Ischyrocerus by 

 Kroyer. Later authors placed it in Podocerus, and Stebbing in 1906 

 returned it to Ischyrocerus. 



Ischyrocerus latipes has been recorded from Spitzbergen, White 

 Sea, Kara Sea, Barents Sea, Jugor Strait, New Siberian Islands, 

 East and West Greenland, and now for the first time from Alaska, 

 where it appears to be quite common. This is a large species, reaching 

 a length of 15 mm. or more. It has been taken down to 350 m. 



The specimens from Hudson Bay identified as /. assimilis (Shoe- 

 maker, 1926, p. 10) have been examined and have been found to be 

 Ischyrocerus latipes Kroyer. 



