CRUSTACEA CASPU. 453 



tinct. The inner ramus, as in most other Caspian species, is very small and 

 scale-like. 



Tlie telsou (fig. 19) has the lateral lobes rather broad and blunted at the 

 tip, each cai-^iug only a single apical spine accompanied by a small hair. 



Occurrence. — Some few specimens of this form are coutained in the 

 collection of Dr. Grimm, having been collected in the bay of Baku, from 

 2 — 6 fathoms. 



14. Gammarus macrocephalus, Grimm. MS. 



(PI. 7, figs. 1—11). 



Specific Characters. — Body somewhat robust, with evenly rounded 

 back. Cephalon of quite an unusual size and strongly convex above, lateral 

 lobes short and broad, transvefsely trnucated at the tip. Co.val plates not 

 particularly large. The last 2 pairs of epimeral plates of metasome acutely 

 produced at the lateral corners. Urosome with the 2 anterior segments pro- 

 duced dorsally to very prominent narrow tubercles tipped by spines; no 

 lateral spines on the 1st segment. Jiyes very small, reniform. Superioi' 

 antennae rather slender, and somewhat longer than the superior, accessory 

 appendage narrow, 6-articulate. Gnathopoda (in male) very unequally de- 

 veloped, the posterior ones being much stronger than the anterior, with the 

 propodos exceedingly large, oval pyriform. Pereiupoda rather slender, and 

 edged with fascicles of short spines, basal joint of last pair moderately ex- 

 panded and produced at the infero-posteal corner to an obtusely-pointed 

 lappet. Last pair of uropoda ratlier elongated, though not attaining the 

 length of the urosome, outer ramus naiTow, sub-lineai", and densely fringed 

 with setse, between which are scattered spines; inner ramus very small. 

 Telson with the lateral lobes narrowly truncated at the tip, and each carry- 

 ing 3 apical spines. Length of adult male 24 mm. 



Remarks. — This species, established by Dr. Grimm, is at once re- 

 cognized by the unusual size and peculiar sliape of tlie cephalon, which 

 character, indeed, would seem to have given rise to the specific name pro- 

 posed by that author. Otherwise it is nearly allied to G. Grimmi, exhibit- 

 ing a rather similar armature of the urosome. 



Description. — The length of an adult male specimen measures about 

 24 mm., and this form accordingly grows to a rather large size. 



As compared with G. Grimmi, the body appears (see fig. 1) somewhat 

 more robust, with the back broadly rounded and quite smootli. 



The cephalon is highly remarkable for its large size and unusual shape. 

 It considerably exceeds in length the fii'st 2 segments of the mesosome com- 



*a3.-MiiT. OTp. 283. 33 31 



