378 MR. G. S. BRADY ON NEW OR IMPERFECTLY 



Van RL-Dis. (PI. LX. fig. 6, a-c.) 



More rounded in outline ; the tubercles and ridges of the carapace ohsolete. Surface 

 undulated, marked with large oval pittings, chiefly on the anterior half of the valves. 

 Posterior extremity bearing a few small teeth. 



Length -^ in. {'36 mm.). 



Hab. Atlantic Ocean (223 fathoms, Commander Dayman's soundings). 



The form which I have named rudis appears in all important characters to agree 

 with the present species (C. lactea). Probably the paucity and indistinctness of its 

 surface-markings may be attributed to the combined effects of old age and peculiarity of 

 habitat. 



14. Cythere pumila, n. sp. (PI. LX. fig. 7, a~d.) 



Carapace compressed, oblong, quadrilateral. Anterior extremity broad, obliquely 

 rounded ; posterior narrow, flattened, produced below. Ventral and dorsal margins 

 nearly straight. Seen from below, the outline of the carapace is compressed, oblong, 

 with parallel sides and truncated pyramidal extremities. Surface covered with strong, 

 irregularly disposed ribs, marking out about four large and several smaller fossae, and 

 dividing somewhat dichotomously towards the anterior margin. 



Length ^ in. ('54 mm.). 



Hab. Australia. One specimen, 



15. Cythere producta, n. sp. (PI. LIX. fig. 11, a-d.) 



Carapace oblong, quadrilateral, convex ; extremities equal. Anterior margin rounded, 

 forming a flattened border, which is much produced at the ventral angle. Inferior half 

 of the posterior border produced backwards into an irregularly toothed process. Dorsal 

 and ventral margins parallel, nearly straight. Dorsal aspect ovate. Surface of the valves 

 marked with quadrangular pits arranged in longitudinal rows, and becoming obsolete 

 towards the dorsal margin. 



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



Hab. Honduras (shallow water in calcareous sand). 



16. Cythere pavonia, n. sp. (PI. LXI. fig. 2, a-d.) 



Carapace oblong, compressed, rather gibbous in the centre, ending posteriorly in an 

 oblique ridge, which forms three crescentiform excavations near the lower posterior 

 angle. The anterior border is broad and well rounded ; the posterior narrow, oblique, 

 and emarginate. Dorsal margin nearly straight ; ventral slightly sinuated. The ventral 

 profile is compressed, lanceolate, showing on the posterior half of each valve three large 

 and deep circular fossae, which are surrounded by elevated borders. These, seen in 

 profile, form the crescentic ridges which are visible on the lateral aspect. Valves 



