62 ZOOLOGY OF THE VOYAGE OF THE SULPHUE. 



Some small milk-white strigae traverse the valves near the umbos in an 

 oblique direction, and are very characteristic. The ribs are very minutely and 

 sharply sculptured, and they retain the same structure on both valves. Each rib is 

 divided by the sulci into about five smaller, the odd one being situated on the 

 summit and giving it a sharp-keeled edge. 



Family — Arcace^e. 



Nucula. Lamarck. 



252. Nucula Cumingii, Hinds, Proceed. Zool. Soc. 1843, p. 97, (Plate XVIII. fig. 1.) Testa 

 elliptica, tenui, epidermide virente induta, antice abbreviata, subrostrata, postice elongata, rotun- 

 data; margine ventrali acuto, antice subemarginato, dorsali postico, prominulo; cardine antice den- 

 tibus 6, postice 19-20. 



Inhab. The Asiatic analogue of N. obliqua, and is widely diffused over the 

 seas of the Indian Archipelago. It has been obtained at New Guinea, Straits of 

 Macassar ; Bolinao, San Nicholas, Sual and Bassey in the Philippines ; Singa- 

 pore ; and Straits of Malacca ; in a depth of water varying from seven to twenty- 

 three fathoms, on a floor of mud and sandy mud. 



It is distinguished from N. obliqua by the disposition to rostration of the 

 anterior limb, prominent dorsal margin, slight indentation at the anterior part of 

 the ventral margin, and larger size. 



253. Nucula mitralis, Hinds, 1. c. p. 97, (Plate XVIII. fig. 2.) Testa conoidali, solidula, 

 epidermide fusca induta, antice brevissime abbreviata, recta. ; margine dorsali postico inclinato, 

 marginibus ventralibus crenulatis ; cardine antice dentibus 10, postice 28-30. 



Inhab. Straits of Malacca. From seventeen fathoms, mud. 



The very contracted and straight anterior margin of this shell gives it the 

 shape of a mitre, or other similar elevated head-dress. 



254. Nucula pulchra, Hinds, 1. c. p. 97, (Plate XVIII. fig. 3.) Testa, elliptica, solida, sul- 

 cata, interstitiis transversim striatis ; marginibus ventralibus crenulatis ; cardine antice dentibus 9, 

 postice 27-29. 



Inhab. LAgulhas Bank, Cape of Good Hope. From seventy fathoms. 



This species very closely resembles N. Duchastelii, Nyst, a fossil from the 

 province of Antwerp, but is rendered distinct by its continuous, not interrupted 

 concentric lamellae, and by its striated instead of smooth lunule. Among the 

 numerous species of Nucula, these two are conspicuous for their strongly marked 

 and distinguishing characters. 



255. Nucula divaricata, Hinds, 1. c. p. 97, (Plate XVIII. fig. 4.) Testa elliptica, antice 



