1901.] CEirSTACEAN FROM THE SOUDAK. 95 



extremities; but between the orbits the crest appears smooth. 

 The mesogastric sutiu'e, 6 mm. long, does not extend to the 

 middle of the space between the postfrontal crest and the 

 transverse groove limiting the mesogastric and the urogastric 

 regions from one another; and this groove, visible immediately 

 behind the middle of the carapace, is very shallow and hardly 

 distinguishable. A little further backwards a similar shallow 

 groove is observed separating the urogastric area from the cardiac. 

 The lateral grooves of the H-sbaped figure are somewhat deeper, 

 and likewise the two >-shaped grooves that bound the anterior 

 cardiac region laterally. The lateral portions of the cervical 

 suture, whic-h in other species run obliquely forward and outward 

 are quite indistinct in Potamon floiveri ; their direction, however, 

 is still indicated by impressed punctures, that are somewhat 

 larger than the minute punctures scattered on the upper surface of 

 the carapace ; the latter are very fine, only distiuguishable by means 

 of a magnifying-glass, and rather few in number. 



The antero-lateral margins of the carapace are strougly arcuate, 

 almost semicircular, bulging out very much laterally ; they extend 

 as far beyond the external orbital angles as the breadth of the 

 orbits. They are defined by a distinctly granulated line that 

 extends backwards as far as the urogastric area. The postero- 

 lateral margins are rounded and smooth and appear very slightly 

 concave, when the carapace is looked at obliquely from above. An 

 epibranchial tooth is wanting. The granulated line that defines 

 the antero-lateral margins, posterior to the postfrontal rid»e, is 

 formed by fifteen or sixteen rather large granules, that are not 

 sharp, gradually decrease in size backwards, and finally disappear. 

 The distance between the epibranchial angles measures four-fifths, 

 and that between the extraorbital angles about two-thirds of the 

 width of the carapace. 



The front is somewhat convex longitudinally, but almost straight 

 transversely, and the width of the free border" measures one-fourth 

 the breadth of the cephalothorax ; the upper surface is smooth, 

 rather closely punctate, and the punctures are slightly larger than 

 those of the upper surface of the carapace. AVhen the latter is 

 looked at from above, the free border of the front appears widely 

 emarginate in the middle ; this anterior margin forms very obtuse, 

 though not rounded, angles with the very oblique lateral margins 

 of the front ; the latter are somewhat thickened, whereas the 

 transverse external portions of the upper orbital margins are 

 thinner. 



The sharp, dentiform, outer angles of the orbits are rather 

 prominent and forvvardly directed. Between the extraorbital 

 tooth and the epibranchial angle there is a granulated tooth or 

 prominence immediately behind the groove that separates the 

 suborbital and subbrancliial areas from one another; this tooth, 

 however, is a little smaller than the extraorbital tooth-. 



The postfrontal crest lies far forwards, so that when the cara- 

 pace is looked at from above a small portion of the upper margin 



