KNOWN SPECIES OF MARINE OSTRACODA. 367 



below, the carapace is oval, compressed. Surface smooth, with scattered hairs. Lucid 

 spots arranged in an obliquely transverse row near the centre of the carapace. 



Length -^ in. (1'05 mm.). 



Hub. AustraUa, 17 fathoms {Prof. Jukes' s soundings). 



Closely related to Cythere minna, Baird, but not much more than one-third of the 

 size, and the posterior extremity is not nearly so acute. The greatest height is about 

 the middle, whereas C. minna is highest near the front. 



2. Cytherideis maculata, n. sp. (PI. LVII. fig. 12, a, b.) 



Oblong, arcuate, compressed, nearly thrice as long as broad. Anterior extremity 

 tapering to a rounded point; posterior broader, rounded, and produced below the level 

 of the ventral border. Dorsal margin arched, highest in the middle. Ventral margin 

 gently incurved, with a median convexity. Surface smooth, white, marked with a 

 large, oval, pellucid central patch, on which are several (generally three) cloudings of 

 opaque white. 



Length ^ in. (1'16 mm.). 



Hab. AustraHa, West Indies, Turk's Island. 



3. Cytherideis gracilis, Feuss. (PI. LVIII. fig. \,a-d.) 



Cytherina gracilis, Reuss (1850), Haidinger's Abhand. Band iii. p. 52, t. 11. f. 3. 

 ? Bairdia lithodomoides, Bosquet, Entom. Fossil, des Ter. Tertiair. p. 36, pi. 2. fig. 3. 



Carapace elongate, subarcuate, convex, about twice and a half as long as broad. 

 Dorsal margin arched; ventral deeply sinuate at anterior, third. Anterior border 

 compressed ; posterior broad, obliquely rounded. Dorsal aspect compressed, ovate. 

 The shell is smooth, transparent, mostly of a yellow tint, and, in some specimens, 

 marked on its anterior portion with several concentric undulations or faint ridges, 

 which run nearly parallel with the margins of the valves. 



Length yg- in. ('73 mm.). 



Hab. Levant (sponge-sand). 



Very nearly allied to Cythere angustata, Von Miinster, but altogether smaller and more 

 fragile, and possibly only a variety of it. I have ascribed my specimens to C. gracilis 

 merely from comparison with the figures of that species, having seen no authentic 

 specimens of it ; and I am not able to detect any vahd distinction between it and 

 C. angustata. 



In outline this agrees very closely with Reuss's figure, and in surface-marking 

 with Bosquet's ; so that it would seem probable that these may properly be re- 

 garded as varieties of one and the same species. Yet, in most of my specimens, the 

 concentric rugae are absent, and in some the sinuation of the ventral margin is scarcely 

 perceptible. 



