112 smith: description of new species of nucut.a. 



incurvati, ad apicem parvi, aci/ti, antice inclhiati ; valves 

 va/idcE, liris ienuibus arcuatis i?i medio et prope anguhim 

 umbonalem viaxivie divaricatis ornatce, linds incremeuii, hie 

 illic cofispiaiis, sculpfce ; ai'ea afifica snhcojicava, sed in medio 

 leviter prominens, liras temdores exhibens ; pagijia intermi 

 albido-margaritacea , 7-adiatim obsolete substriata, ad mai- 

 ginem inferioreni tenuissime subereuulata ; cicatrices subce- 

 quales, irregulariter rotundatce ; denies cardinis validi, acuti, 

 anteriores circiter 7/ndecim, posteriores, qiionim pauci infra 

 apicem Jiiininii, circa 23 ; fossa iiganienti mediocris, postice 

 inciinata. 



Longit. 36^- niilli/n., alt. 25, diani. 16. 



Hab. : Bay of Bengal, off the mouth of tlie River HugH, in 

 deep water. 



This species is remarkable for its large size, the very 

 inequilateral valves, and the fine divaricate sculpture. The 

 anterior extremity forms a decided but short beak. Near this, 

 but a little behind the curved umbonal ridge, the valves exhibit 

 a shallow depression or groove, which radiates from the ventral 

 margin, where it terminates in a slight insinuation towards the 

 umbones. The raised lirae diverge or divaricate not only at a 

 line which runs from the apices to the lower margin bisecting 

 the valves into about equal parts, but also at the umbonal 

 angle. The epidermis is yellowish towards the umbones, but 

 becomes browner and darker towards the outer margin, 

 especially posteriorly. 



In many respects this fine species resembles A^. mirabilis 

 (Adams and Reeve) from the Japanese Sea. It is, however, 

 larger (being the largest living species of the genus Nucula 

 yet described), has a yellowish epidermis, and is more triangular 

 in form. The ventral outline is more broadly arcuate and less 

 sinuated anteriorly than in N. 7nirabilis, the umbones are less 

 terminal, the anterior or rostrate end is more produced, and the 

 inner edges of the valves are less distinctly crenulated. 



J.C, vii., Oct., 1892. 



