RECENT BRITISH OSTRACODA. 



445 



sinuated in front of the middle." The shell is closely punctate and divided (especially 

 in the male) into large polygonal areolae. " Colour deep blackish green towards each 

 extremity, with an obliquely transverse white median band. Last joint of the upper 

 antennae elongated, equal in length to the preceding; second joint of the last pair of feet 

 much longer than the two following joints ; terminal claw curved toward the apex. 

 Copulative organs of the male large, basal portion subquadrangular, with a very long 

 convoluted tube, distal portion obtusely rounded below, divided behind into many irre- 

 gular processes, of which the lower is large and obtusely pointed." 

 Length in. 



The only specimen of C. gibha which I have seen is a female, in the collection of the 

 E/CV. A. M. Norman. The locality in which it was taken is unknown. 



13. Cytherura cornuta, n. sp. (Plate XXXII. figs. 12-15.) 

 Distribution : Recent — Britain, Dardanelles. 



Carapace of the female, as seen from the side, subquadrangular, nearly equal in height 

 throughout ; height equal to half the length. Anterior extreinity broadly rounded, pos- 

 terior produced above the middle into a large obtusely rounded beak ; dorsal margin 

 gently arched ; ventral abruptly sinuated in front, produced behind into a sharply defined 

 crest, which terminates in an acute triangular lamina or spine. Outline, as seen from 

 above, somewhat hastate, broadest behind the middle, pointed in front, strongly mucro- 

 nate behind ; greatest width equal to more than half the length. End view triangular, 

 nearly equilateral, base fiat and produced at the angles. The shell is faintly sulcate in 

 the middle, the anterior portion marked with almost obsolete polygonal depressions, the 

 posterior irregularly reticulated ; ventral surface longitudinally striated, waved. 



Length ^ in. . . V/ fv-*~>~ 



Hab. Birterbuy Bay, 10 fathoms, amongst mud (G. S. B.) ; Cumbrae and Shetland [Mr. D. Robertson) ; 

 Loch Erribol (Mr. D. O. Dreioetf) . 



C. cornuta is evidently nearly allied to the preceding species, but is distinguished by the 

 acutely angular ventral ala, the less rounded outline, more prominent posterior beak, 

 weaker reticulation of the surface, and, lastly, by its larger size. From C. acuticostata it 

 is separated chiefly by the character of the surface-markings. 



14. Ottheuura acuticostata, G. O. Sars. (Plate XXXII. figs. 1-11.) 



Cytherura acuticostata, G. O. Sars, loc. cit. p. 76. 



Atlantic type. Distribution : Recent — Norway, Great Britain, Ireland. Fossil — Norway, glacial. 



Carapace of the female very tumid; seen from the side, subquadrangular, greatest 

 height somewhat exceeding half the length ; broadly rounded in front, posterior margin 

 waved, obliquely truncate, and produced above the middle into a rather slender beak ; 

 superior margin gently arched, slightly depressed in front ; inferior slightly sinuated, 

 and terminating behind in an acute angular spine. Outline, as seen from above, broadly 

 ovate, mucronate behind ; width equal to more than half the length. The male more 

 elongated, higher in front than behind, the superior and inferior margins more distinctly 



