326 THE VOYAGE OF H.M.S. CHALLENGER. 



towards which the umboncs incline, somewhat straighter, the crenulation or dentition 

 within the margin of the valves is less developed, and the hinge-teeth appear to be 

 fewer. The character of the external sculpture, however, is exactly similar, and possibly 

 were a larger series of specimens at hand, the above slight differences would prove to be 

 inconstant. 



Area (Bai'batia) pteroessa {vide p. 262). 



Habitat.— S>tiition 237, June 17, 1875; lat 34° 37' N., long. 140' 32' E.; depth, 

 1875 fathoms; bottom, blue mud (off the south-east coast of Nipon, Japan). Also 

 Station 16, March 7, 1873; lat. 20° 39' N., long. 50° 33' W.; depth, 2435 fathoms; 

 bottom, Globigerina ooze (Mid North Atlantic, east of the West Indies). 



It is interesting that other specimens of this species have come to hand which were 

 obtained from the Pacific, being confirmatory of its existence in that and the Atlantic 

 Oceans. 



Ai-ca [Scapharca) incBquisculpta {vide p. 267). 



Habitat. — Station 5, south-west of the Canary Islands, in 2740 fathoms. 



A single half-grown example in perfect condition from the above locality shows that 

 this species is, as I suspected, inequivalve, and therefore belongs to the section 

 Scapharca. It is clothed with a thin pale brownish epidermis, which, under a strong 

 lens, presents a finely hairy aspect, the short hairs arising from the points of intersection 

 of the slender concentric and radiating lirse. It is interesting to find this species also 

 occurring on the eastern side of the Atlantic, more than 2000 miles from the only other 

 locality whence at present it has been obtained. 



Spondylus ostr-eoides, n. sp. 



Testa parva, altior quam longa, alba, infsquivalvis. Valva superior ii-regulariter 

 planiuscula, incrementi lineis concentricis lamellatis confertis undulatis sculpta. Valvae 

 inferior — ? (tubulis vermium, &c., obtecta). Pagina interna alba, nitida, cicatrice 

 musculari subrotundata distincta notata. Margo valvse supei'ioris denticulis minutis 

 remotis intus instructus, valvse inferioris fossis vel puncturis congruentibus sculptus. 



The single specimen obtained is of small size, and consequently may not be adult. 

 It is of the same general form as many other species of the genus, but is remarkable 



