385 Dominican Fossils— Maury 221 



ridges, as in T. punicea and alternata, but very much feebler. 

 On the right valve the ridges extend over the shell as far as the 

 anterior edge of the umbonal ridge where they end, only a few- 

 being continued as raised concentric threads. On the left valve 

 the concentric ridges are present only on the anterior end then 

 fade out, so that the central and posterior portions of the shell 

 are smooth except for very fine concentric growth-lines. Both 

 valves show in certain lights faint, obsolete radial striae ; both 

 valves show a distinct anterior and posterior sulcus, the former 

 near the anterior dorsal margin, the latter on the umbonal ridge. 

 Interior of valves with a radial rib just behind the anterior ad- 

 ductor scar ; cardinal and lateral teeth very strong in the right 

 valve, the anterior lateral especially conspicuous, posterior cardi- 

 nal tooth bifid ; teeth of the left valve weaker or obsolete ; pallial 

 sinus very deep, extending to the anterior adductor scar. Length 

 of average; sized shell 41, altitude 22, diameter 9, that of the 

 left valve being 5, that of the right 4 mm. This pretty species is 

 referable to the section Eurytellina. 



Localities. — (Exp'd '16) Zone H (abundant), Zone I 

 (scarce), Rio Cana at Caimito. 



Tellina islahisapanioltz , n. sp. 



Plate 38, Figure 6 



We collected two right valves of a very delicate, fragile Tell- 

 ina at once differentiated by its exquisite microscopic sculpture. 

 The left valve is as yet unknown. Right valve oblong, greatly 

 compressed, umbonal ridge angulated, with a broad sulcus be- 

 hind, rendering the posterior margin of the shell arcuate ; concen- 

 tric sculpture of extremely fine, close, rounded threads extending 

 to the umbonal ridge where they are replaced by less regular, 

 arcuate growth-lines continuing to the dorsal margin ; radial 

 sculpture of fine incised lines absent from the posterior dorsal 

 region, commencing just anterior to the umbonal ridge ; for 

 some distance they are close-set and regularly spaced, cutting 

 trie concentric thread into rectangular blocks, but towards the 

 center of the valve and anteriorly the radii become more distant, 



