'102 G. 0. SAES, [T. XIII 



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 

 Mysidae, 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 an 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 their correctness is thus 

 guaranteed. 



Gen. 1. Paramysis, Czerniavsky, 1882. 



Generic characters. — Form of body (PI. I, fig. 1, PI. II, fig. 1) rather 

 robust. Carapace well-developed, and but slightly emarginated posteriorly, 

 its lateral lobes completely obtecting the sides of the mesosome (see PI. II, 

 fig. I), 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 

 antennae (PI. I, fig. 3) of the usual structure, male appendage (see PI. II, 

 fig. 1 & 2) well-developed and densely hirsute. Inferior antennae (PI. I, 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 to a 

 strong spiniform projection, tip of the scale transversely truncated, with the 

 inner corner not at all produced, and the apical segment nearly obsolete 

 (see PI. I, fig. 5). Anterior and posterior lips (PL I, figs. 6 & 10), as also 

 the mandibles (figs. 7 & 9) of normal structure. First pair of maxillae (PL II, 

 fig. 3) with the exognath less rudimentary than usual, having in front seve- 

 ral strong plumose setae wanting in other Mysidae. Second pair of maxillae 

 (PL II, fig. 4) with the terminal joint of the palp oblong oval in form and 

 carrying along the outer edge strong, partly ciliated setae, exognath of a 

 somewhat unusual form, its outer edge being strongly curved so as to form 

 a broadly rounded lobe, marginal setae very unequal, the proximal ones 

 being extremely strong and elongated. Maxillipeds (PL II, fig. 5) with the 



Bulletin N. S! IV (XXXVI) p. 54. 



