200 BULLETIN 201, UNITE© STATElS NATIONAL MUSEUM 



a synonym of Neomysis. Ii's description is very detailed and com- 

 plete and agrees very closely with the specimens here recorded. 



N. mirdbilis has well-marked grooves and ridges on the last thoracic 

 somites and incipient grooves and furrows on the first five abdominal 

 somites. The furrows on the abdominal somites are sometimes very 

 difficult to see and are much fainter in the young than in fully grown 

 specimens. 



The telson is very characteristic, linguiform in shape, with sinuous 

 lateral margins and a rounded apex. The spines are coarse, rather 

 blunt and closely set. In some specimens the spines in the center of 

 the lateral margins show a tendency to be arranged in groups, but the 

 smaller spines between the larger ones are only slightly smaller than 

 the latter and the grouping is not nearly so well marked as in N. 

 czerniawskii, wherein the smaller spines are much smaller than the 

 long spines and more numerous (figs. 78, c-d, 79, b). In other speci- 

 mens (fig. 78, c) the grouping of the spines is almost completely ob- 

 scured. The apex has only one pair of spines, and there is no pair of 

 small spines between them. The species grows to a large size, 30 mm. 

 in the female and 25 mm. in the male, though females of 16 mm. occur 

 in the collection with eggs in the brood pouch. I counted 40 embryos 

 in the brood pouch of a large female. There are sternal processes on 

 the seventh and eighth thoracic sterna of the female and a baling lobe 

 on the anterior oostegite. 



N. mirdbilis is most closely allied to N. czerniawskii but may be 

 distinguished by the different arrangement of the spines on the telson 

 and by the somewhat different proportions of the joints of the exopod 

 of the fourth pleopod of the male. The two species often occur to- 

 gether, and I think that the young specimens attributed to N. ander- 

 soni (N. czerniawskii) by Schmitt are in reality N. mirabilis. 

 Schmitt's figure 3a is remarkably like that of the telson of N. mirab- 

 ilis. Schmitt noted the differences and attributed them to age, but 

 in the present collection there are young specimens of N. czerniawskii 

 that have the telson exactly as in the adult. 



NEOMYSIS CZERNIAWSKII Dershavin 



FlGUBE 79 



Neomysis, cserniaivskii Dershavin, 1913, p. 199, figs. 5-7. — Tatteksall, 1933, 



p. 11.— Ii, 1936a, p. 585, figs. 14-21. 

 Neomysis andersoni (pars) W. L. Schmitt, 1919, p. 6, figs. 1, 2, 3b. 



Occurrence. — Bering Sea region: Chamisso Harbor, Eschscholtz 

 Bay, Alaska, 5 to 8 fathoms, W. H. Dall collector, 3 adult males, 5 

 immature males, 2 not quite adult females, up to 20 mm.; Grantley 

 Harbor, Port Clarence, Alaska, August 3-4, 1913, at surface, 1 female, 

 Neomysis andersoni Schmitt cotype; Petropavlovsk, Kamchatka, 



