KNOWN SPECIES OF MARINE OSTRACODA. 375 



over the central portion in an angular network ; but towards the margins the pattern 

 becomes more lax, longitudinal rows taking the place of the meshes. 



Length :^ in. ('GS mm.). 



Hah. Norway {Messrs. M' Andrew and Barrett's dredgings). 



Cythere kostelensis, Reuss, as figured by Egger (Die Ostrak. der Miocan-Schicht. t. 4. 

 fig. 4), is very similar in form and general characters to our C. catenata. Reuss's 

 original figure is, however, very different ; and both authors concur in ascribing to 

 C. kostelensis a pitted surface, the former adding that minute tubercles are found 

 between the " thickly set pores," which on the ventral surface are replaced by delicate 

 furrowings. C. catenata, however, is wholly devoid of pittings, and is ornamented only 

 with minute projecting spines or bosses. 



10. Cythere septentrionalis, n. sp. (PI. LX. fig. 4, «-/.) 



Oblong, subquadrilateral, convex. Anterior margin broad and obliquely rounded ; 

 posterior narrower and somewhat flattened. Dorsal margin straight, with a slight 

 convexity in the middle, and sloping gently backwards from the anterior hinge. 

 Ventral margin somewhat convex. Surface marked with large angular pittings, 

 which gradually coalesce towards the margins, forming on the ventral surface sharply 

 cut longitudinal furrows. The pitted or reticulated sculpture prevails on the central 

 parts of the dorsal and lateral aspects ; but over the whole ventral surface longitu- 

 dinal grooving only is visible. Dorsal aspect ovate. Mid view broadly ovate, flattened 

 and grooved below. 



Length -^ in. (1-27 mm.). 



Hab. Hunde Islands, 60-70 fathoms {Dr. P. C. Sutherland's dredgings). Many 

 specimens. 



This is possibly allied to a Tertiary (Eocene) species, C. scrobiculata, Munster. 

 There is, indeed, less difl"erence between the recent C. septentrionalis and some 

 figures of the fossil C. scrobiculata than between some of the fossil forms referred 

 by different authors to the latter species. Dr. Baird remarks also that his C. quadri- 

 dentata is nearly allied to C. scrobiculata as originally described by Von Miinster. It is, 

 however, very widely different from the present species. The marks which I should 

 especially insist upon as diagnostic of C. septentrionalis are the strong development of 

 the anterior hinge, and the oval outline and distinct longitudinal fluting of the ventral 

 aspect. But the whole group to which it belongs is a perplexing one, its various 

 members running into each other by imperceptible gradations, which, to my mind, 

 speak plainly of one common origin. 



11. Ctthere costata, n. sp. (PI. LX. fig. 5, a-f.) 



Carapace compressed, oblong, narrowed posteriorly. Anterior margin rounded, and 



