NO. U39. DEi:r-rrjTER IHILU'SCJI'ERRILL JXD nrsn. 881 



showing only very minute papilla- posteriorly. The foot is large and 

 strong, with a broad, strongly crennlated and striated, concave disk, 

 pointed in front. The gills are well developed and somewhat triquetral, 

 The palpal tentacles are rather large, long, tapered, triquetral, strongly 

 grooved, curved in sickle-shape. The palpi are rather broad and short. 



The following are some of the known species: 



T. arata Bellardi, and T. solida Segueuza, fossil, in the Italian ter- 

 tiary formation; T. cytherea Dall = T. veneriforiitia (Smith), T. amahiUs 

 Dall, T. vi rents Dall, T. acinulti Dall, T. cuneata (Smith) = T. smith ii 

 Dall, T. lata Verrill and Bush, all Florida and West Indian species; 

 and T. callixtiformis Verrill and Bush, off Chesapeake Bay. 



TINDARIA CALLISTIFORMIS Verrill and Bush. 

 (Plates LXXVIII, tig. 1; LXXX, figs. 6, 7.) 



Tindaria cullistifurmis VERRILL and Rrsir, Amer. Journ. Sri., Ill, p. 59, figs. 10, 

 20, 21, January, 1897. 



Shell small, stout, thick, regularly ovate, sculptured with very regu- 

 nlar, tine, concentric grooves, and having a broad, thick hinge margin 

 with a continuous line of teeth and no chondrophore. limbos swollen, 

 beaks prominent, strongly curved inward and somewhat forward, with 

 the nuclear shell (prodissoconch) smooth and glossy. The lunular 

 area is somewhat excavated but has no definite boundary. Anterior 

 end considerably shorter than the posterior, both equally and evenly 

 rounded. Antero dorsal margin convex, sloping rather rapidly and 

 forming a continuous curve with the anterior margin which is also 

 continuous with the more broadly convex ventral margin : the poste- 

 rior end is evenly rounded, with the dorsal margin strongly convex, 

 sloping gradually, without any definite angulation. The surface is 

 covered with very regular, fine, close, concentric, rounded ridges, sepa- 

 rated by semicircular furrows about twice their width, except on the 

 limbos where the two are about equal. The inner ventral margin is 

 plain, sharp, and slightly beveled. The hinge-margin is wide and 

 thick, narrowest just behind the beaks, gradually widening and thick- 

 ening toward both ends. The anterior portion is much the shorter and 

 somewhat the wider and slopes more rapidly; along the narrow mid- 

 dle portion the teeth are quite small, but regular, transverse, and sep- 

 arated by narrow intervals; owing to the absence of a chondrophore, 

 there is no definite center, but in front of the tip of the beaks there 

 are about eight teeth which increase rapidly in size and prominence, 

 the four distal ones being large, elevated, and somewhat V-shaped; 

 behind the beak there are about twenty-three teeth, of which nine or 

 ten proximal ones are small; they then commence to increase in size 

 and length so that eight or nine are larger and higher than the rest; 

 these are, however, smaller and more acute than the larger ones in the 

 anterior portion ; two or three distal ones are a little less elevated than 

 Proc. N. M. vol. xx 50 



