V II L A D M Y A. 



(ienus PHOLADOMYA, Soworby. 

 Ttsin liivalvis, wqnivalvis, transven^e ohlotiga, tenuis, 

 utriiiijue hiaiis, cosiis radiata, antici brevibiis, /wftice 

 pioductu, giibtriincatis. Cardo foveola elongato- 

 mhtrigona et lamina mnryinali in vlrurpie valvd. 

 Ligamentum externum, hrevinscvhnn. Imprescioni-s 

 musculares duce, indistinctce. ; ■pallii imprcssio late 

 siituata. 

 Shell bivalve, equivalve, transversoly oblong, tliin, 

 gaping on both sides, rayed witli riUs, short in 

 front, produced and snbtnincated posteriorly. 

 Hinge with an elongated, subtrigonal pit and a 

 marginal lamina in each valve. Ligament external, 

 rather short. Muscular impressions two, indistinct; 

 impression of the mantle ^videly sinuatcd. 

 The one recent species known of this .-iingularly 

 isolated genus is from the island of Tortola. on the 

 shores of which it is sometimes, but very rarely, tlirown 

 up by violent ocean .storms. It is a revival of a very 

 ancient fossil form, of which there are numerous well- 

 known species. The worn hole in the umboes observed 

 in all the specimens, results from their close approxi- 

 mation, causing them to rub against eacli other with 

 the action of the valves. 



fFiL-. .^ />, c, Mas, 



/'// 



;'"/'.' 



epid,nniil, toiiii, lii„,il,i. ■ 

 tricvsd, riigasd, tniii>i-ii 

 brevi, subrutuiidd, hilr In 

 obliquis nodii lifer in, in lilt 



V-<i<Wi, alba, 

 (liai/i itti, ven- 

 latere antico 

 rti'inU'i, medio costis 

 lalis radiata ; latere 



uhb.n 



posiico producto, lati: hianti, subUsvigato, suboblique 

 truncato, margine dorsali rectiiisculo, ventrali postice 

 siibinjlato ; umhonibus prominenlibns, approximatis, 

 perforatis. 



The white PiioL.\noMV.\. Shell papyraceous, white, 

 covered with a thin striped epidermis, subiridescent, 

 ventricose, rugose, transversely oblong; anterior side 

 short, a little rounded, broadly gaping, wrinkled, 

 rayed in the middle with oblique noduliferous ribs; 

 po.sterior side produced, widely gaj)ing, rather 

 smooth, rather obliquely truncated, dorsal margin 

 rather straight, ventral posteriorly a little inflated ; 

 umboes prominent, approximate, perforated. 



SuWEUHY. Genera of Eecent and Fossi! Shells. 



Hub. Island of Tortola. 



