P H L A S. 



Species 4. (Fig. a. b, Mus. Jeffreys.) 



Pholas dacttlus. Plio. testd antice aperld, rostratd, 

 elongcUd, posiice subattenuatd ; costis angulatis, 

 acutisdme spinis imbricatis, medio et versils exti-e- 

 mitatem posticuvi evanidis ; margine dorsali antice 

 reflexo, fulcro concamerato duplicatv ; valvulis 

 dorsalibus anlicis duabus, nucleis postico-latera- 

 libiis; und posticd elomjald angustd. 



The date Pholas. Shell anteriorly open, rostrated, 

 elongated, posteriorly subattenuated ; ribs angular, 

 very acutely imbricated with spines, disappearing 

 towards the middle and posterior extremity ; 

 dorsal margin reflected in front, doubled by a 

 chambered fulcrum ; dorsal valves two anterior, 

 with postero-lateral nuclei ; one posterior, elon- 

 gated, narrow. 



LiNN^Ds. Systema Natura?. 



Hab. Various parts of Great Britain, in sandstone. 



Species 5. (Fig. a, b, Mus. Brit.) 

 Pholas orientalis. Pho, testa antice apertd, rotundd, 

 costis subrotundis, imbricatis, crebris dimidiatiin 

 armatd, postice Imvigatd attenuatd, acuminatd; 

 valvulis dorsalibus und untied, laid, nucleo sub- 

 antice, und posticd elongatd angustissimd. 

 The oriental Pholas. Shell anteriorly open, rounded, 

 armed halfway with rather rounded, imbricated, 

 numerous ribs, posteriorly smooth, attenuated. 



acuminated ; dorsal valves one anterior, broad, 

 with subanterior nucleus, one posterior elongated, 

 very narrow. 

 Gmehn. No. ;321G. 



Species C. (Fig. a, b, Mus. Brit.) 



Pholas Chiloensis. Pho. testd svbcylindricd, elongatd, 

 antice apertd, rotundaid ; omnino costis rotundis 

 siibdistantibus, obtuse intncatis, postice subobsoleiis, 

 radiatd ; valvidis dorsalibus duabus anticis, latis, 

 nucleis antccentralibus approximatis ; und posticd 

 parvd transversd; alterd posticd elongatd an- 

 gustd. 



Thb CniLOEAN Pholas. Shell subcylindrical, elon- 

 gated, anteriorly open, rounded ; rayed all over 

 with rounded, rather distant, obtusely imbricated, 

 posteriorly subobsolete ribs; dorsal valves two 

 anterior, wide, with ante-central approximated 

 nuclei; one posterior, small, transverse; anotlier 

 posterior elongated, narrow. 



King. Zoological Journal, vol. v. p. 334. 



Hab. Chiloe. H. Cuming. 



Pholas Campecliensis. Gmaliu. 



The two accessory valves covering the umboes liave 

 their nuclei elevated and close to each other, while in 

 those of Pholas dactylus they are depressed, posterior, 

 and on the outer edges. 



March, 1872. 



