428 6- 0. SAR8, 



Sweden and Russia, as also of North America. Botli species are certainly of 

 true arctic origin. To these species may now be added a 3rd, peculiar to 

 the Caspian Sea, and well defined from any of the others. 



3. Pontoporeia microphthalma, Grimm. MS. 



{PI. 2, figs. 1-7). 



Specific Characters. — Body moderately slender and somewhat com- 

 pressed. Cephalon with the lateral lobes narrowly rounded. (!o.\al and epi- 

 meral plates nearly as in P. afftnis. Urosome rather short and stout, with 

 the 1st segment considerably elevated dorsally at the posterior edge, and 

 having in the middle 2 minute juxtaposed denticles, on each side a single 

 small spine. Eyes comparatively small, irregularly oval in form. Antennae 

 nearly as in P. affinis. Anterior gnathopoda with the carpus moderately 

 expanded, propodos oblong oval, with the palm rather short and imperfectly 

 defined below. Posterior gnathopoda with the propodos narrow oblong and 

 transversely truncated at the tip. Last pair of pereiopoda with the basal 

 joint very large, rounded oval, posterior edge regularly curved througliout. 

 Uropoda and telson of the usu<al structure. Length 6 mm. 



Remarks. — The present new species, detected by Dr. (Trimm, is nearly 

 allied to P. affinis Lindstrom, but easily distinguishable by the compara- 

 tively smaller eyes, the dorsally produced 1st segment of the urosome, and 

 the more regular form of the basal joint of the last pair of pereiopoda. Also 

 in the form of the propodos of the 2 pairs of gnathopoda, some differences 

 are to be found. 



Description. — The length of the only tolerably well preserved specimen, 

 apparently an adult female, scarcely exceeds 6 mm., and this form is ac- 

 cordingly rather inferior in size to the other 2 known species. 



The general form of the body (see fig. 1 ) resembles that in the other 2 

 species, being moderately slender, and somewhat compressed, with the meso- 

 some and metasome quite smooth throughout. 



The cephalon about equals in length the first 2 segments of the meso- 

 some combined, and is somewhat produced in front between the bases of 

 the superior antennae (see fig. 3). The lateral lobes are slightly prominent, 

 and narrowly rounded at the tip. 



The anterior pairs of coxal plates are somewhat deeper than the cor- 

 responding segments, and densely fringed at the end with ciliated setae. The 

 1st pair are a little broader than the 2nd, but scarcely at all expanded distally. 

 The 4th pair are slightly emarginated posteriorly, and somewhat expanded in 

 their outer part, forming beneath the emargination an obtuse-angular corner. 



■l-Ha.-UaT. CTp. 258. 8 



