54 Go. SARS, [ντ . 
The disintegration of the genus Mysis, as formerly defined, into seve- 
ral distinct genera, according to the different structure of the antennal 
scales, the telson, and the pleopoda in the male, was first proposed by Mr. 
Czerniavsky in his above cited work. In a subsequent paper on the British 
Mysidæ, the Rev. Mr. Norman has adopted a similar subdivision of the 
genus, but in some cases he disagrees with Mr. Czerniavsky, as regards 
the limitation of the genera. Under these circumstances it would seem to be 
appropriate to give ap exhaustive diagnosis also of the genera, to which the 
Caspian Mysidae ought to be referred. 
It may be added, that I have had an opportunity of examining some 
of the’ type specimens of Czerniavsky, which were kindly sent to me from 
the Zoological Museum in St. Petersburgh for comparison and identification. 
-» All the plates have been prepared by the autographic method, which 
the author has applied in several of his other works, and which I think 
may answer the purpose very well. The figures have in every case been ori- ' 
ginally drawn by the aid of the camera lucida, and eg correctness is thus 
E 
Gen. 1. ga Ml uted ne 1882. 
Generic characters. Form of body (Pl. I, fig. 1, Pl. 1, fig. 1) rather 
robust. Carapace well-developed, and but slightly emarginated ‘posteriorly, 
its lateral lobes completely obtecting the sides of the mesosome (see Pl. II, 
fig: D, cephalic part well defined by a conspicuous cervical sulcus, and hav- 
ing the anterior edge evenly curved in the middle; ! frontal! spine (see Pl. I, 
fig. 2) large, uncovered. Eyes (ibid) comparatively short and thick. Superior 
antenne (Pl. I, fip. 8) of the usual structure, male) appendage (see Pl. IL, 
fig. 1 & 2) well-developed and densely hirsute. Inferior antennæ (Pl. L fig. 
4) Having the basal part considerably produced at the exterior corner, scale 
very large, with the outer edge quite smooth and produced at the end {9:8 
strong spiniform projection, tip of the scale transversely truncated, with the 
inter corner not at all produced, and the apical: segment nearly: obsolete 
(see Pl. 1, fig. 5). Anterior and posterior lips (Pl. I, figs. 6 & 10); as also 
the mandibles (figs. 7 & 9) of normal structure. First pair of maxille (Pl. H, 
fig. 3) with the exognath less rudimentary than usual, having in front seve- 
ral strong plumose setze wanting in other Mysidæ: Second pair of maxilla 
(P1. II, fig. 4) with the terminal joint of the palp oblong oval in form and 
carrying along the outer edge strong) partly ciliated seta, exognath of a 
somewhat unusual form, its outer edge being strongly curved so as to'i form 
a broadly rounded lobe, marginal sete very unequal, the proximal ones ` 
| DONE extremely strong and elongated. Maxillipods. (Pl, fig. 5) with the 
E T. XIII, p. 402, 
A5 1). ἘΣ R z Ga E Ze d d Ze 
