COXIBCIIOM'S PEOM MELAITESIA. 



22. Fetricola lapicida. 



Venus lapicida, Chemnitz, Crni-Cah. x. p. 356, figs. 1664-5 ; Sowerhy, 

 Cmch. Icon. (Petricola) figs. 22, 24 ; Martens in Von der Beckenh 

 Reisen in Ost-Afrika, vol. iii. p. 66, pi. 3. figs. 3 a, b. 



Hob. West Indies {Chemnitz, d'Orhigny, Sfc.) ; North Australia 

 {J. B. Elsey in Brit. Mus.) ; West Island, Prince of Wales Channel, 

 Torres Straits {Coppinger) ; Zanzibar {Peters, teste Martens). 



This and the Venus divaricata of Chemnitz I regard as one species, 

 and from his description of the former it seems probable that he had 

 before him specimens which to a great extent had lost the fine zigzag 

 sculpture mentioned in his description of the latter. The raised 

 oblique ridges from the umbones down the posterior slope have 

 various degrees of development in different specimens, in some existing 

 only near the posterior margin of the valves, whilst in others they 

 extend the whole distance from the beaks downwards, and, again, in 

 young shells they may be altogether wanting. These ridges are 

 easily removed, and seem to be superimposed upon the zigzag sculp- 

 ture beneath. After a careful examination of Austrahan specimens 

 and others from the West Indies, I cannot detect any material 

 specific differences. 



The example figured by Dr. E. von Martens as P. divarieata is 

 unsuaUy peaked at the umbones. 



23. Fsammobia modesta. 



Deshayes, Proc. Zool. Soc. 1854, p. 319 ; Beeve, Conch. Icon. fig. 3. 



Hah. Port Jackson {Coppinger) ; Moreton Bay {Deshayes). 



The single specimen before me is father narrower than that 

 figured in the ' Conchologia Iconica,' is purplish lilac within for the 

 most part, yellowish near the muscular scars, and exibits the pinkish 

 rays on the ventral margin. The epidermis is brightish yellow. 

 Oblique strise are sometimes present at the central portion of the 

 valves, but are not conspicuous. 



24. Psammobia gracilenta. (Plate VII. figs. B-B 2.) 



Shell concentrically striated, transversely elongate, very inequi- 

 lateral, almost twice as long as high, not very compressed, dirty 

 whitish with a few diaphanous zones and several light reddish 

 narrow rays beneath a thin pale yellowish-oHve epidermis, very 

 narrowly gaping at both ends. Anterior dorsal margin of the valves 

 about twice as long as the posterior, subrectilinear, and nearly 

 parallel with the ventral. Hinder dorsal edge oblique, a little 

 arcuate. Lower margin straightish, obliquely curving upward in 

 front and more sharply turning at the opposite extremity. Interior 

 bluish white, iridescent, exhibiting the reddish rays. Beaks small, 

 adjacent, posteriorly inclined. Ligament short, but prominent, placed 

 on a conspicuous ligamental plate in each valve behind the umbones. 

 A second minute ligament exists immediately in front of them and 



