Paleontology Zorritos Formation 35 



SYSTEMATIC PALEOXTOLOGY 



Class GASTROPODA 



Superorder Streptoneura 



Suborder Orthodonta 



Order CTENOBRAXCHIATA 



Super family Toxoglossa 



Family TEREBRIDAE 



Genus Terebra Adanson 



Terebra gausapata var. heniderana n. var. 



Plate I — Fig. i. 



Shell small, delicate, sharply sculptured, the apical angle 

 very small. The fasciole is sharply defined, of medium 

 width. Spiral sculpture on the main part of the whorl of 

 about eight unequal bands separated by narrower inter- 

 spaces. On the fasciole are vestiges of a spiral sculpture 

 of about three or four fine threads, situated on the upper 

 half of the fasciole. Longitudinal sculpture of sharp ribs, 

 17-18 to the whorl, which are not crossed by the spiral 

 bands. These ribs are cut by the suture on one side of the 

 fasciole, where they offset, the rib of one whorl abutting 

 against the interspace on the fasciole of the succeeding 

 whorl. On the other side of the fasciole they are cut by a 

 deeper suture. The body whorl is rounded, and is larger 

 than the preceding whorls. The typical sculpture continues 

 across the base to the columella. The whorls are convex 

 between fascioles. The inner aperture is not known. Height 

 of fragment showing body whorl and two of the spire, 13.5 ; 

 maximum, diameter, 5.25 mm. 



This varietv differs from T. gausapata Brown and Pils- 

 bry -*> from Gatun, in being somewhat larger, having 17-18 



Proc. Ac. Xat. Sc. Phila., vol. 63. p. 340, pi. 22, figs. 8, 9, 191 1. 



