398 Gould's Descriptions of Shells 
In that species the hinge has only a single tooth, stouter or with an 
obsolete one at its base. 
TELLINA TERSA (PlI.XVI. Fig. 2.) 
modica, convexiuscula, ovato-triangularis, alba, concentricé vix striata: 
sri xocitéiisÉ; latere antico rotundato, superne compresso; latere postico 
ngulari, apice sabat, margine dorsali recto, citò desinente : denti ibus late- 
bie obsoletis 
Shell moderately large, inequilateral, rather convex, ovate-trian- 
gular, white, varied with milky and watery white zones; incre- 
mental striæ fine and irregular; apex one fifth nearest the poste- 
ior end, which is triangular, (the dorsal slope very rapidly 
declining,) slightly truncate at tip, the submarginal flexure well 
marked; anterior half broadly rounded, dorsal edge somewhat 
compressed ; ventral margin regularly arcuate ; lateral teeth want- 
ing, or consisting of a slight submarginal ridge. 
Diameters, longitudinal one inch; vertical seven tenths of an 
inch; transverse three tenths of an inch. 
Inhabits Panama. Col. Jewett. 
It has a general resemblance to T. lineata, Turt., but is smaller, 
thinner, more compressed, and has no lateral teeth. It is more 
closely allied to T. plebeja, but is more equilateral and quite white. 
It has so few obvious characters that it is very difficult to describe. 
TELLINA PURA (Pl. XVI. Fig.3.) 
T. parva, sub-elliptica, vix inequilateralis, tenuis, lucida, vel zonis lacteis 
zonata, striis minutissimis radiata ; apice acuto ; latere antico semi-ovali ; later? 
postico modicé angustato, truncato, hiante, plicá admodum eiecit jcuá: 
nitida, striis elevatis tenuibus radiata; dentibus lateralibus carentibus 
Shell small, compressed, suboval, nearly equilateral, thin and 
lueid except where obscured by zones of opaque white, shining; 
with numerous microscopic radiating stri; ; apex acutely elevated ; 
anterior half semi-elliptical, rounded at extremity ; posterior half a 
little narrowed, the dorsal margin declining in nearly a right line, 
tip moderately truncate. Within, shining, and marked by nume- 
rous minute, raised, radiating lines ; lateral teeth wanting. 
Diameters, longitudinal, one inch; vertical three fifths of an 
inch ; transverse three tenths of an inch. 5 
