1917.] NATURAL SCIENCES OF PHILADELPHIA. 35 



formed by a couple of contiguous threads on a slight elevation, at 

 the lower fourth of the whorls. The base is somewhat convex, and 

 shows four very low, wide spiral welts, with the same finer spirals 

 as the upper surface. The parietal callus is heavy. Length of the 

 fragment figured 47 mm.; diameter, 24.5 mm. 

 Turritella lloydsmithi n. sp. PI. 5, fig. 11. 



This large species has some resemblance to T. gatunensis, the taper 

 being about the same. The whorls are flat except at the periphery 

 (or above the suture) where they bulge a little. This is most marked 

 on the later whorls. The very faint growth-lines are slightly arcuate. 

 Sculpture of about six low spiral cords unevenly spaced, those on the 

 bulging lower part being coarser. The base shows about 7 strong 

 spiral cords; over all there is a minute sculpture of unequal spiral 

 threads. The suture is impressed and distinct. A specimen retaining 

 five whorls measures 64.6 mm. long, 23.8 mm. in greatest diameter. 



This species differs from T. subgrundifera and its allies by the 

 sculpture, and from T. gatunensis by sculpture and the shape of the 

 whorls, which are not excavated above. 



Turritella subgrundifera Dall. 



Turritella suhgrimdijera Dall, Trans. Wagner Inst., Ill, pt. 2, 1892, p. 313^ 

 PI. 22, fig. 23. 



We are unable to distinguish these specimens from subgruyidifera 

 . from near Bailey's Ferry, Chipola River, of which we have compared 

 a good series. Whether T. atacta Dall of the Tampa silex bed differs 

 specifically seems somewhat doubtful, but the specimens known are 

 smaller. 

 Turritella domingensis n. sp. PI. 5, figs. 7, 7a, 9. 



In the adult stage there are two approximate spiral cords, one at, 

 the other above the periphery. Above this there are five spiral 

 threads, the upper two close together, the others about equally 

 spaced. The median part of the whorl is lightly concave, with very 

 strongly arched growth-ridges at wide intervals. Over all there is a 

 minute sculpture of slightly waved, irregular, sometimes anastomosing 

 striae, spiral and parallel on the lower part of the whorl, converging 

 forward from each growth-ridge on the median part of the whorl. 

 In the young shells, up to over 20 mm. in length, the ridge above 

 the suture is acute and strong, the median concavity and the superior 

 convexity are much more marked, and usually some of the median 

 threads are beaded. The largest piece, of about 3 whorls, measures: 

 length 37.3, diam. 18 mm. 



Santo Domingo, W. M. Gabb. Type No. 2611, A. N. S. P. 



