ACEPHALA. 409 
most conspicuous at margin, the reverse of the exterior; lateral teeth 
undeveloped. 
Length seven-tenths of an inch; height four-tenths of an inch. 
Habitat unknown. 
About the size, form, and colouring of ‘I. Valtonis, Hanley, which 
appears to be a polished, pellucid shell, with no peculiarity of sculp- 
ture. It is very near to T. rhomboides, Quoy, which is said to have 
fine, concentric striz anteriorly, that become obsolete at the middle. 
Figure 514, outside of the shell, enlarged; 5144, interior of the 
shell; 5146, dorsal view, in outline. 
TELLINA PERULA (Gould). 
T. parvula, sokdiuscula, ventricosa, rotundato-triangularts, eburnea, con- 
centricé et remote striatula; apicibus tumidis, submedianis, radiis 
bints lactets ornatis ; marginibus dorsalibus valdé dechvibus ; latere 
antico rotundato, tumido ; latere siphonali brevi, valde flexuoso, infra 
angulato; margine ventral pendulo; cavositatis limbo albo, disco 
sulphureo ; dentibus lateralibus conspicuts. 
Tellina perula, Goutp; Proceed. Boston Soc. Nat. Hist., iti. 254. 
June 1850. Expedition Shells, 80. 
SHELL minute, rather solid, polished and shining, subequilateral. 
ventricose, subglobose, rounded ovate-triangular, ivory-white with two 
milk-white umbonal rays on the beaks; beaks a little behind the mid- 
dle; anterior dorsal edge nearly rectilinear, extremity acutely rounded ; 
posterior dorsal margin rapidly sloping, rectilinear; tip acute, slightly 
truncated; flexure angular, well marked; ventral margin pendulous or 
much arcuated; centre of the disk tumid; surface having distant, very 
shallow, concentric grooves; shell broadest at the middle; within, 
white at margin, sulphur-yellow centrally, with the two white rays in 
the cavity of the beaks corresponding to those on the outside: well- 
developed lateral teeth at both ends. 
103 
