﻿M Y T I L I M E R I A. 



Genus MYTILIMERIA, Conrad. 

 Testa bivalvis, bimtisculosa, tenuis, subccquivalvis, valde 

 inceqiiilateralis, epidermide induta. Umbones 

 spirales, subdistanter. Cardo edentulo ; cartilagine 

 partim in foveam instructa, lamina testacea libera 

 obteHo. 

 Shell bivalve, -with two muscles, thin, subequivalve, 

 very inequilateral, covcr<'<l with an epidermis. 

 Umboes spiral, rather distant. Hinge without 

 teeth, with a cartilage placed partly in a hollow, 

 partly covered by a free testaceous plate. 

 The type of this genus is the roiinded oval shell 

 named M. Nuttalli by Conrad. The specimens in the 

 British Museum are odd valves, the shelly plates of 

 which are missing. The subsequently discovered large 

 shell from Vancouver's Island, which has been de- 

 scribed as L/jonsia saxicola by Dr. Baird, is fairly well 

 adjudged to belong to this genus, and has the ossicle 

 well developed. 



Species 1. (Mus. Brit.) 

 MyTiLiMERL\ Ndttalli. Myt. testa rotundc ovatu, 



tenici, alba; umbonibus leiiiiinalibus, diatantibus, 



valide spiralibus ; latere postico erpanso, terminibus 



tnincatis. 

 Nutt.\ll"s Mytilimeria. Shell roundly ovate, thin, 



white ; umboes terminal, distant, very spiral ; 



posterior side expanded, ends truncated. 

 Conrad. Amer. Journ. Sci. 

 Hub. California. 



The cartilage is placed in a narrow spiral groove 

 running from the umbo, and where it comes to the 

 hinge line it is enlarged. 



Species 2. (Mus. Brit.) 

 Mytilimei'.ia DiAPHANA. Mi/t. tcstd semtpellucida, 

 ohlongd, arcuatd, linguiformi, subcomplanatd, super 

 aream posticam tceniis fuscis plurimus radiatd ; 



umbonibus elevalis, fere ierminalibiis ; latere postico 

 ad terminum late Iruncato ; margine dorsati 

 arcuatim depresso. 



The DIAPHANOUS Mytilimeiua. Shcdl semitransparent, 

 oblong, curved, tongue-shaped, rather flattened, 

 rayed on the posterior area with several brown 

 bands; umboes raised, nearly terminal ; posterior 

 side broadly truncated ; dorsal margin depressed 

 with a curve. 



Carpenter (Li/onsia). Proc. Zool. Soc, 1855. 



Ilab. California. 



Species 3. (Mus. Brit.) 



Mttflimeria I'LIC.\t.\. ^lyt. testa parvd, lavigald, 

 cuneatd ; antice sinuatim plicatd', postice expansd ; 

 umbonibus acuiis, fere terminalibus ; latere antico 

 brevissimo, acuminata, margine ventrali profunde 

 sinuate ; latere ])03tico alato, infra marginem 

 dorsalem depresso, margine ventrali inflalo. 



The plaited Mytilimeria. Shell small, smooth, 

 wedge-shaped, anteriorly sinuously plaited, pos- 

 teriorly expanded ; umboes acute, nearly ter- 

 minal ; anterior side very sliort, acuminated ; 

 ventral margin deeply sinuated ; posterior side 

 alated, depressed below the dorsal margin, ventral 

 margin inflated. 



Gray-. MS. Brit. Mus. 



Hab. ? 



Species -1. (Mus. Brit.) 

 Mytilimeria sa.\icola. M;it. testd luagnd, ventricosd, 

 oblongd, epidermide valido, corneo-indutd, ad niar- 

 gines ventralem et terminalum hianti ; latere antico 

 brevi, angusto ; latere postico elongate, ventiicoso, 

 ad terminum tmncato ; valvd dextrd planiusculd 

 valvd siuistrd profunde ventricosd ; margine dorsali 

 depresso, arcuato ; laiiiind cardinali magnd, crassd, 

 extus convexd. 



May, 1875. 



