179 



Gen. 38. Xenocythere, G. O. Sars, n. 



Generic Characters. Shell cuneate in shape, much higher in front than 

 behind, with the ventral face broad and flattened. Valves subequal, moderately 

 strong, with the inner duplicatures rather broad in front and crossed by scattered 

 pore-channels. Hinge with the edges minutely crenulated in the middle, closing 

 teeth imperfectly developed. Eyes confluent. Antennae comparatively short and 

 stout, the anterior ones with the terminal part triarticulate and armed in front 

 with 3 clawlike spines, the posterior ones with only a single apical claw ac- 

 companied posteriorly by a very small spine. Vibratory plate of mandibular 

 palp comparatively small, with only 3 setae, the anterior one rudimentary. 

 Maxillae with the masticatory lobes rather produced, palp comparatively narrow. 

 Legs moderately slender, basal part with only a single seta of the anterior 

 margin. Caudal lamellae rounded in shape, with 2 comparatively small bristles. 

 Copulative appendages of male large, with the basal part remarkably high, 

 terminal part triangular in shape. 



Remarks. This new genus is only founded on a single species, which 

 however exibits some rather distinct differences from the other genera here 

 recorded, both as to the general shape of the shell and to the structure of 

 some of the appendages. 



82 Xenocythere cuneiformis (Brady). 



(PI. LXXXII). 



Cythere cuneiformis, Brady, Monogr. Brit. Ostnacoda, p. 404, PI. XXXI, figs. 47 54. 

 Syn : Cythere ventricosa, G. O. Sars (not Speyer). 



Specific Characters. Female. Shell, seen laterally, oblong sublavate in 

 shape, tapering behind to an obtuse point; greatest height quite in front, and 

 about equal to half the length, dorsal margin gibbously bent in the ocular 

 region and sloping rather steeply behind at a nearly straight course, ventral 

 margin very slightly sinuated, anterior extremity obliquely rounded off, posterior 

 rather narrow and exerted below to an obsusely conical prominence; seen 

 dorsally, broadly ovate in outline, with the greatest width about half the length, 

 lateral margins slightly concaved in the middle, anterior extremity obtusely 

 pointed, posterior abruptly contracted to a projecting conical prominence. Sur- 

 face of valves indistinctly pitted, and more or less conspicuously rugose longi- 

 tudinally, being clothed at each extremity with scattered fine hairs. Anterior 

 antennae with the last joint about half the length of the penultimate one. 



