60 6.0. SARS, (sam 
what remote from the tip, apical sinus (see fig. 15) rather shallow, though 
well-defined, and bordered by about 24 regular dentiform projections acute 
at the tip, terminal lobes slightly diverging, and each tipped by a rather 
strong spine. Inner lamella of the uropoda (fig. 13) moderately tumefied at 
the base, with the otolith well-developed; inner edge armed, below the mar- 
ginal sete, with about 9 spines, the outermost of which is placed at some 
distance from the others, not far from the tip. Body without any: distinct 
dendritic ramifications, but having along the back the usual pigmentary 
centres. Length of adult female reaching 21 mm. 
Remarks. — As above stated, this form was referred by Mr. Czer- 
niavsky to his genus Paramysis. This is evidently quite erroneous, for it 
is in all characteristics a true Mesomysis, as seen both from the above 
description and the appended figures. In order to decide the question with 
full certainty, I have felt justified to dissect one of the type specimens in 
the collection of Czerniavsky. From the other species belonging to the 
present genus, this form may at once be distinguished by its unusually 
slender and elongated body, and the comparatively large telson. Besides the 
typical form, Mr. Czerniavsky also records a variety ,,forma occidentalis“, 
which, however, most probably is only founded upon an immature specimen 
of the typical form. 
Occurrence. — According to Mr. Czerniavsky, 4 adult female speci- 
mens of this form were collected by Lieutenant Ullsky in the mouth of the 
Wolga, and thus probably in nearly pure fresh water. Another specimen 
was, according to the same author, captured in the northern part of the 
Caspian Sea, and a third immature specimen, that upon which the variety 
„Occidentalis“ was founded, was apparently from Petrowsk or Baku. In the 
collection of Warpachowsky this species was not represented. Except in 
the Caspian Sea it has not yet been recorded. 
3. Mesomysis Kowalevskyi, Czern. 
(PI. IV). 
Mesomysis Kowaleceky, Czerniavsky, l. c. fasc. 2, p. 50, Pl. XXI, Pl. XXII, figs 1—13. 
= Specific Characters. — Body (Pl. IV, fig. 1) not nearly so slender as in the 
preceding species, and having the metasome much less prolonged. Carapace 
evenly emarginated posteriorly, cephalic part fully as broad as the Ist seg- 
ment of metasome, its anterior edge (see fig. 2) somewhat arched in the 
middle, without, however, obtecting the frontal spine, which projects freely 
beyond the edge. Eyes (ibid.) rather large, pyriform, projecting somewhat 
beyond the sides of the carapace, corneal part well-developed, and, as usual, 
emarginated on the dorsal face. Antennal scales (fig. 9) mh in shape 
Mélanges biologiques. T. XIIT, p. 408. 
