P H L A S. 



Ill, 



Species 7. (Fig. a, h, Mas. Cum. in Brit.) 



Pholas constricta. P/to. testd breviusculd, arUice 

 rostratd, ulrinque late apertd ; in medio post 

 sulcum foveolatum oblique divisd et constricld ; 

 antice ventricosd, radiatim scabrosd, j)Ostice an- 

 gusld, ininule conceiitrice siriatd ; marline domali 

 super umhones rejlexo. 



The constricted Pholas. Shell rather short, ante- 

 riorly rostrated on both sides, widely o)ieu in the 

 middle, behind a pitted groove obliquely divided 

 and constricted; ventricose in front, i-adiately 

 scabrous, narrow behind, minutely concentrically 

 striated ; dorsal margin reflected over the umbocs. 



SowERBr. Proc. Zool. Soc, 1849. 



Hah. Straits of Sunda. 



Like Pliolas parra in form, bnt more strongly 

 tightened in the middle and destitute of a dorsal plate. 



Species 8. (Fig. a, b, Mas. Cum. in liHt.) 



Pholas fkagilis. Pho. testd elongatd, nmjustd, antice 

 apertd, acute rostratd, costellis acute imhricatis an- 

 tice posticeqne radiatd ; hand medio C07istnctd, 

 margine dorsali rejlexo, valvuld dorsali unicd super 

 umbones locatd. 



The fragile Pholas. Shell elongated, narrow, open 

 in front, acutely beaked, rayed witli acutely im- 

 bricated little ribs ; not constricted in the middle ; 

 dorsal margin reflexed, a single dorsal valve 

 placed upon the iimboes. 



SowERBY. Proc. Zool. See, 1848, p. 10. 



Hab. Bassy, Island of Samar, Philippines, in soft stone 

 at low water. H. Cuming. 

 Very narrow and fragile, and not, like Pholas parva, 



narrow in the middle. The beaked part in front of 



the umboes is much smaller. 



Species 0. (Mus. Brit.) 



PhOL.VS CRISPATA. Pho. test') lnli). lurilio /irr .^iilcum 



foveolatum divisd, antler hilr (ij„:ri,i. ro.-.lnilii. tri- 

 gond costis acutissime iinhrii-itlis railin/i'i. miinjiup 

 dorsali T'flixo, I'entrali acute laqwato ; /lostice 

 Iwvigato, brevi, subrotundato ; valvuld dorsali 

 nulla. 



The crisp Pholas. Shell wide, separated in the 

 middle by a pitted groove, anteriorly widely open, 

 beaked, trigonal, rayed with very acutely imbri- 

 cated ribs ; posteriorly smooth, short, rather 

 rounded ; no dorsal valve. 



LiNN^us. Systema Natura". 



Hab. Groat Britain. 



In this broad and short well-known species, the tubes 



of the mollusc are protected by an external epider- 



midous case. 



10. (Mus. Brit.) 



Pholas simii.ks. Pho. te.itd latiusculd, fragili, ventri- 

 cosd, antice latissime apertd, acutissime rostratd, 

 costis acutissime imbricatis subdistantibus radiatd, 

 'inar'/iiir liimiti spini/ero ; medio et postice concen- 

 tri,r nnj.ii.i. fix radiatd; valvuld dorsali unicd, 

 super Kiiilioiir.^ locatd nucleo postice terminah. 



The similar Pholas. Shell rather broad, fragile, 

 anteriorly widely open, very sharply beaked, 

 rayed with very sharply imbricated rather distant 

 ribs, gaping margin spiniferous ; in the middle 

 and posteriorly concentrically ridged, scarcely 

 rayed ; dorsal valve single, placed upon the 

 umboes with terminal nucleus. 



Gray. MS. 



Hab. New Zealand. Earle. 



Jlore ventricose than Pholas parra, and narrowed 



in the middle. 



March, 1872. 



