No, 1591. SCHIZOPODS FROM ALASKA—ORTMANN. 3 
pairs of marsupial lamelle, and should be placed in a distinct 
subfamily. 
The genera Amblyops G. O. Sars* and Pseudomma G. O. Sars? 
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 Leptomysine, being 
not cleft. 
The genera Lrythrops, Parerythrops, and Huchetomera seem to 
form a natural group, differing from the typical Leptomysine 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 very uniform, the second to fifth having 
subequal branches. | 7 
Of the other genera, Leptomysis, 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 Lrythrops 
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 J/ystnae; 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 J/ysinw, one branch being rudimentary, the other 
greatly developed. 3 
The genus Callomysis Holmes®¢ 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 ¢hird pair in the male, in which the 
outer ramus is elongated, much after the style in certain Mysine. 
Monogr. Mysid., II, 1872, p. 3. 
’Tdem, I, 1870, p. 48. 
© Proe. Cal, Acad. Sci. (2), LV, 1895, p. 582. 
