410 G. 0. SARS, [t. XIII 



Black Sea, viz., Odessa andOczakow, being in the first-named place extract- 

 ed from the ventricle of Perca fluviatilis, together with M. intermedia. 



4. Mesomysss Czerniavskyi, G. 0. Sars, n. sp. 

 (PL V.) 



Specific Characters. — Very like the last species, though perhaps a 

 little more slender in form (see PI. V, fig. 1). Carapace having the cephalic 

 part scarcely narrower that the 1st segment of metasome, its anterior edge 

 evenly curved in the middle, frontal spine uncovered. Eyes (see fig. 2) pyri- 

 form, reaching somewhat beyond the sides of the carapace, corneal part 

 well-developed and distinctly emarginated on the dorsal face. Antennal 

 scales (see fig. 3) exceeding the peduncles of the superior antennae by about 

 % of their length, and oblong linear in form, but very little attenuated 

 distally, terminal part in front of the outer corner (fig. 4) occupying about 

 Y 7 of the length of the scale, apical segment well-defined. Pereiopoda (fig. 6) 

 and pleopoda (figs. 12, 13) in both sexes of much the same structure as in 

 M. Kowalevskyi. Telson (fig. 8) scarcely longer than the last segment of meta- 

 some, and about twice as long as it is broad at the base, outer part somewhat 

 attenuated, lateral edges but very slightly flexuous, and armed each with 

 about 18 spinules, apical sinus (see fig. 9) extremely shallow, nearly obso- 

 lete, its edge bordered with 16 — 18 regular dentiform projections, spines 

 of the outlier corners not very strong. Inner lamella of the uropoda (fig. 1 0) 

 not much tumefied at the base, and having the otolith very small, inner edge 

 armed, below the marginal setse, with about 7 spines, the 3 outer ones being 

 somewhat wider apart than the 4 inner. Body without any distinct dendritic 

 ramifications, though having the usual dorsal pigmentary centres. Length 

 of adult female reaching 1 8 mm. 



Remarks. — The present new species, which I have named in honour 

 of the distinguished Kussian naturalist Mr. Czerniavsky, is very nearly 

 allied to M. Kowalevskyi, though apparently distinct, differing, as it does, 

 rather conspicuously in the want of the rich dendritic ramifications orna- 

 menting the body of the former species, and also by the apical sinus of the 

 telson being so very shallow as nearly to be obsolete. 



Occurrence. — Some specimens, females and males, of this form were 

 contained in the collection of Warpachowsky, and occurred at Stat. 27, 

 lying at the southern point of the Island of Kulaly, north of the peninsula 

 Mangischlak. 



Bulletin N. S. IV (XXXVI) p. 62. 



