s. Slioll slinrt, cTuipate, closed, 

 grecnisli epidermis, constricted in 



SHOUT Piio 

 covered witli 

 tlif middle, anteriorly inflated at the ventral mar- 

 ifin ; dorsal shield small, broad ; dorsal margin 

 slijrhtly ex])anded posteriorly and anteriorly. 

 i;i:r.Y. Thesaurus Conchyliorum, Pholas, fig. 105. 



PIIOLAS.— Plate VII, 

 Tin; nv,\Ti: 



Species ■2V. (Fig. a, /-, Mns. Brit.) 



PHfiL.vs ov.\T.\. FIio. tei<td jiyrifornii, ventricosd, clausd, 

 ill medio tiunaversc iHvisd, antice latei-c dorsali 

 railiatniii costiitd, oblique striatd, latere ventrali 

 inflato, Iceriijato ; posticc larignid, valvulis longi- 

 tudine inaqualilnis ; iimhonibiis lamind testaced 

 axjinnsd celatis. 



: Pholas. Shell pyriform, ventricose, closed, 

 divided transversely in the middle, anteriorly 

 radiately ribl)cd at the dorsal side, inflated and 

 smooth on the ventral side ; posteriorly smooth, 

 with the valves unequal in length ; umboes hidden 

 by a shelly, expanded jilate. 



Gray. MS. in Mus. Brit. 



//„/,. ? 



This species, unique as far as known, in the British 

 Museum, has some relation to the several species 

 united in Sowerby's Thesaurus Conchyliorum under 

 the name " Ti{I0MPHAll\," .said to be identical with 

 " Jmanettia" but it has not the false umbo and over- 

 lapping anterior margin in one valve wliich characterizes 

 the genus- in (juestion, and its covering jilate or shield 

 is independent. 



