KNOWN SPECIES OF MARINE OSTRACODA. 371 



Lucid spots about four, in a transverse row, with one or two more detached from and in 

 front of the main group. 



Hab. Hunde Islands, 25-30 fathoms (Dr. Sutherland). Norway {Messrs. M' Andrew 

 and Barrett) British north-eastern and north-western coasts, 20-46 fathoms. 



Length yj in. ('84 mm.). 



A species allied to Cytheridea pinguis, Jones. Of frequent occurrence both on the 

 eastern and western shores of the North Sea. It is one of the commonest of living 

 species in the deep water oft" the Northumberland and Durham coasts. I have also seen 

 fossil specimens collected by Messrs. Robertson and Crosskey, of Glasgow, from the 

 glacial clay of that district. 



6. Cytheridea MtJLLERi, Von Miinster. (PI. LVIII. fig. 11, a-d.) 



Cythere mulleri, Von Miinster, Leonhard und Bronn's Jahrbuch (18.30), p. 62 ; and Neues Jahrbuch, 



&c. (18.35), p. 446. 

 Cytherina mulleri, Reuss (1850), Haidinger's Abhandl. Band iii. p. 55, t. 8. fig. 21. 

 Cytheridea mulleri. Bosquet, Ent. Fossil, des Terrains Tertiaires, p. 39, pi. 2. fig. 4 a-f. Jones, Monog. 



Tert. Entom. p. 41, pi. 5. figs. 4,5; pi. 6. figs. 10, 11, 12. Egger, Ostrak.,der Miociin-Schicht. 



p. 18, t. 2. fig. 7. Speyer, Ostr. der Casseler-Tertiiirbild. p. 48, t. 1. fig. 8. 



Valves elongated, siliquose, tapering to the posterior extremity, twice as long as broad. 

 Anterior border rounded, and armed with a variable number of sharp spines. Dorsal 

 margin arched, and forming a regular curve as far as the posterior ventral angle, which 

 is somewhat produced. The ventral margin is straight or gently sinuated. Dorsal 

 profile oval. The surface of the shell is marked with subquadrate pits arranged in lon- 

 gitudinal series. 



Length -^ in. ("74 mm.). 



Hab. Mouth of Hermus, Smyrna ; Australia. 



Genus Cythere, Miiller. 



Carapace mostly convex, varying in outline, but mostly oval or irregularly oblong, 

 and highest beneath the anterior hinge, the anterior (and sometimes the posterior) 

 hinge forming indistinct angles on the dorsal margin. The hinge occupies the middle 

 portion of the dorsal margin, and consists, on the right side, of a ridge with two ter- 

 minal teeth, the anterior of which is the most strongly developed. The hinge-margin 

 of the left valve exhibits two fossse for the reception of the teeth of the right valve. 

 The anterior fossa sometimes forms a complete circular perforation of the marginal 

 plate. Between the terminal depressions there is a longitudinal groove adapted to the 

 bar of the opposite valve, and also two terminal projections, much smaller than those 

 of the right valve. The bar and furrow are in many cases obsolete. The edges of the 

 carapace are often produced into thin projecting laminae, especially on the anterior and 



8 c2 



