302 THE VOYAGE OF H.M.S. CHALLENGEE. 



Pecten kermadecensis, n. sp. (PL XXI. figs. 7-7«). 



Testa fragilis, tenuissima, pellucida, valde compressa, valvis diverse sculptLs. Valva 

 dextra liris gracillimis confertis concentricis instructa, sinistra liris concentricis magis 

 distautibus radiatimquc pulcherrime squamulatis ornata. Auriculfe inaeqnales, anticis 

 majoribus, in valva dextra autica inferne sinuata, porca angusta marginata. superne 

 cristulata. Umbones mediocriter acuti, lateribus divergentibus rectis. 



Only two valves described above were obtained, and it is even possible that they do 

 not both belong to one and the same species. They are about as long as high, very thin 

 and fragile, transparent whitish, very much flattened, and ornamented with different 

 sculpture. The right has fine close-set concentric lirse, which become a trifle more 

 pronounced as the shell increases. The left also bears numerous rather more remote and 

 more elevated concentric lirse, supporting many radiating series of small scales, of which 

 one or two indications are visible in the right valve. The ears are unequal, the antei'ior 

 being conspicuously larger than the posterior. The front one in the right valve is 

 sinuated beneath, and is margined along the oblique dorsal slope by a smoothish ridge, 

 which is concave ou the reverse side. The lines of growth are conspicuous on the ears, 

 and in the right valve are produced upward, forming a crested edge to the hinge-line. 

 The beaks are moderately acute, having an apical angle of about 108°, the converging 

 lines being rectilinear. 



Length 7^ mm., height 7^, diameter 2^. 



Habitat. — Station 171, north of Kermadec Islands, at a depth of 600 fathoms. 



This is a fragile species, and probably, living at such a depth, never becomes much 

 thickened. 



Pecten pudicus, n. sp. (PI. XXI. figs. 8-8^). 



Testa tenuissima, planulata, paulo iugequivalvis, albida, hand nitida, concentrice valde 

 plicata, plicis utrinque attenuatis, undique confertim et tenuiter lirata. Auriculae 

 insequales, anticis majoribus, antica valva; dextras liris gracilibus paucis squamulatis 

 ornata, inferne profunde sinuata. 



Length 18:^ mm., height 20, diameter 5. 



Habitat. — Station 146, east of Marion Island, in 1375 fathoms; Globigerina ooze. 



This beautiful species is very like Pecten fragilis of Jeffreys, but appears to differ 

 somewhat in form and in having both valves similarly plicate and lirate. The auricles 

 also are not " equal in size," the anterior being decidedly larger than the posterior. 



The right valve is rather flatter than the left, and its anterior auricle is deeply incised 

 underneath, the upper half of it being ornamented with four or five finely squamate 

 slender lirae. 



