158 STUDIES IN GEOLOGY, No. 3 



The shape of these European species is distinctively differ- 

 ent, but the hinge is closely similar to that of T. sapota- 

 lensis. , , 



Lower Zorritos. Head of Quebrada Zapotal. 



Section EURYTEXUNA 



Tellina (Eurytellina) aequicincta n. sp. 



PLATE X Fig. 3. 



Tellina (Eurytellina) sp. Dall, Trans. Wag. Inst, vol. 3, pt. 5, 

 p. 1024, 1900. 



Tellina (Eurytellina) sp. ind. Woodring, The Mollusca of the Bow- 

 den Beds of Jamaica, Ms. 



Shell medium-sized, moderately thick for size, long, of 

 elegant appearance. Anterior margin rounded, produced ; 

 ventral margin long and nearly straight. Posterior margin 

 biangular. Umbones pointed, terminal. Surface flattened 

 but convex ; a posterior sulcus from the beak to the anterior- 

 most marginal angle is the only sharply curved part of the 

 shell. Sculpture of concentric flat-topped ribs with finely 

 graven interspaces, about 8 in 5 mm. near the margin, and 

 growing finer toward the beaks. The sculpture is sharply 

 curved at both ends of the shell, and is parallel to the 

 margin, in straight lines over most of its length. Escutcheon 

 long and narrow. Hinge and inner shell not known. Length, 

 38; height, 22; (semi) diameter, 4 mm. 



The beautiful sculpture of T. aequicincta gives it clear 

 distinction from the other Tellinas in the collection, none 

 of which approach it in delicacy of external finish. The 

 Bowden form mentioned by Dall and Woodring as noted 

 in the synonymy appears to be sufficiently close to justify 

 uniting it with aequicincta, at least until further material 

 from the Bowden beds is available for comparison. Frag- 

 ments of the Bowden form show the same characteristic 

 sculpture, with the slight difference that the concentric lines 

 are a bit more closely spaced in the Bowden specimens, 



