no. 1591. SCHIZOPODS FROM ALASKA— ORTMANK 3 



pairs of marsupial lamella?, and should be placed in a distinct 

 subfamily. 



The genera Amblyops G. O. Sars a and Pseudomma G. O. Sars h 

 probably belong in this subfamily, but differ from all other genera 

 in the rudimentary condition of the eyes, which are lamelliform. 

 The male pleopods are here very uniform in shape, the first with the 

 inner branch rudimentary, the four others with subequal branches. 

 The telson resembles rather that of the typical Leptomysinw, being 

 not cleft. 



The genera Erythrops, Parerythrops, and Euchcetomera seem to 

 form a natural. group, differing from the typical Leptomy since in the 

 shape of the telson, which always is remarkably short, and mostly 

 has no lateral spines. In this group the male pleopods, as in the 

 Amblyops group, are also yery uniform, the second to fifth having 

 subequal branches. 



Of the other genera, Leptomy sis, Mysidopsis, Mysideis, and the 

 new genus Holmesiella described herein, again form a natural group, 

 characterized by a peculiar development of the male pleopods, which 

 are not so uniform as in the genera mentioned above; in the fourth 

 pair one of the branches develops the tendency to become longer than 

 the other, bearing at the same time a peculiar armature at the apex. 

 The telson in all these forms is distinctly longer than in the Erythrops 

 group, and invariably possesses marginal spines. This group, which 

 may be called the typical one of the Leptomysinae, since it conforms 

 best to the original diagnosis of the subfamily, forms a transition to 

 the subfamily Mysinae; in fact, the latter differs only in a greater 

 accentuation of the differentiation of the male pleopods, not only 

 the first pair, but also the second, and generally also the fifth showing 

 distinct reductions, bearing only one ramus as in the female. Some- 

 times this reduction even affects the third pair. The difference of 

 the two branches of the fourth pair has become very strongly pro- 

 nounced in the Jfysince, one branch being rudimentary, the other 

 greatly developed. 



The genus Gallomysis Holmes c differs from all other genera in the 

 subfamily Leptomysinae in the shape of the pleopods of both, male 

 and female. Here, according to Holmes' account, the pleopods of 

 the female are rudimentary, but biramous, while they are uniramous 

 in all other genera; and also the male pleopods are small and rudi- 

 mentary, although all distinctly biramous ; and further, differing from 

 all other genera, here it is the third pair in the male, in which the 

 outer ramus is elongated, much after the style in certain Mysinse. 



a Monogr. Mysid., II, 1872, p. 3. 



6 Idem, I, 1870, p. 48. 



c Proc. Cal. Acad. Sei. (2), IV, 1895, p. 582. 



