202 BULLETIN 201, UNITED STATES NATIONAL MUSEUM 



marked dorsally and fading away laterally; they are much more 

 prominent than in N. mirabilis. (2) The antennal (fig. 79, a) scale 

 is 14 times as long as broad. (3) The sixth joint of the endopod of 

 the third to the eighth thoracic limbs is divided into 9 to 12 subjoints. 

 (4) The telson (fig. 79, b) is narrowly triangular in shape, nearly 

 three times as long as broad at the base, apex narrowly truncate, al- 

 most rounded, armed with two pairs of spines, the inner of which is 

 half the length of the outer ; lateral margins armed with a continuous 

 series of spines extending from the base to the apex ; in the proximal 

 third of the margin the spines, 17 in number, are more or less regularly 

 spaced without small spines between them; on the distal two-thirds 

 of the margin there are 11 large spines, increasing in length toward 

 the apex, and between each pair of large spines there are 5 to 7 con- 

 spicuously smaller spines. (5) The fourth pleopod of the male (fig. 

 79, c) has the proximal joint of the exopod seven times as long as the 

 distal; the terminal setae are strongly barbed and twice as long as 

 the distal joint. 



The specimens from Tokomai, Japan, agree with Ii's specimens 

 in having the apical spines of the telson all of equal size, but the 

 northern specimens have the inner pair only half as long as the 

 outer. In spite of this difference I think that Ii's specimens and the 

 present material belong to the same species. I have already expressed 

 the opinion (1933) that N. andersoni Schmitt is synonymous with 

 this species. His figure of the telson of the adult agrees closely with 

 that of the present specimens. The young specimens, which Schmitt 

 doubtfully referred to N. andersoni, I now think should be referred 

 to N. mirabilis. 



N. czerniawskii is closely related to N. mirabilis but differs in the 

 arrangement of the spines on the lateral margins of the telson. In 

 N. mirabilis the spines are stouter and blunter, those at the apex are 

 all of equal size, and in the center of the margins where the spines tend 

 to be arranged in groups the smaller spines between the larger ones 

 are longer and fewer than in N. czerniawskii, so that the grouping 

 arrangement is not so obvious as in the latter species. There are also 

 differences in the fourth pleopod of the male. Both species have the 

 free thoracic somites and the first five abdominal somites ornamented 

 with grooves and ridges, but these are more pronounced in N. 

 czerniawskii than in N. mirabilis. In this character these two species 

 differ from all the other species of the genus but some species 

 of the allied genus, Acanthomysis, A. costata, A. sadpta, and A. 

 stelleri, are similarly ornamented. 



NEOMYSIS PATAGONA Zimraer 



Synonymy and distribution records may be found on page 247. 



