ABT. 22 MIOCENE GASTEOPODS AND SCAPHOPODS MANSFIELD 55 



anterior member is always stronger and originates first while the 

 posterior one is borne upon the upper slope of the lower and is the 

 last to appear. The median concavity is marked with about two 

 beaded secondary spirals and by tertiary ones between and on either 

 side of the secondaries. The two primary spirals are crenulated at 

 their summits and in strength are about equal. The type of Turritella 

 tornata Guppy from Cumana, Venezuela, may be a young individual. 

 This differs mainly from my specimens in having a much weaker 

 spiral thread on the upper slope of the posterior spiral and two 

 within the median concavity. 



Figured specimens : U. S. Nat. Mus.. Cat. No. 352676. 



Occurrence. — Middle or lower Miocene : In flood-wash, 8302, Caroni 

 County, Montserrat Ward, 1 mile south of Brasso ; 9215, Caroni 

 County, Montserrat Ward, Brasso railroad station, stream wash; 

 9219, Guaico-Tamana Road. 2 chains east of mile 13 from junction 

 with Eastern Main Road. 



TURRITELLA aff. T. PERATTENUATA PRAECELLENS PiJsbry and Brown 

 Plate 9, tigs. 7. 8 



Turritella perattenuata praecellens Pilsbry and Brown, Acad. Nat. Sci, Phila. 



Proc, vol. 69, p. 36, pi. 5, fig. 12, 1917. 

 Turritella altilira var. tornata Maury (part), Bull. Anier. Paleont, vol. 10, 



no. 42, p. 230. (Not Turritella tornata Guppy.) 



There are several imperfect specimens that appear closely related 

 to T. peratteniMta prdecellens Pilsbry and Brown from the Domin- 

 ican Republic. They all possess two equally strong, crenulated pri- 

 mary spiral cords, the posterior one being double, with its posterior 

 member being a little weaker. The median concavity is rather nar- 

 row and is usually spirally marked with one very fine thread. In the 

 latter feature it differs from the Dominican form, as that is marked 

 with several cords within the median concavity. These specimens 

 tentatively compared with the Dominican species may prove to be dis- 

 tinct species when better material is procured but at present they 

 hardly warrant a specific designation. 



Occun^ence. — Lower Miocene : Narviva County, Charuma Ward, 

 Machapoorie Quarry; Figured specimens (U, S. Nat. Mus. Cat. No. 

 352677). 



TURRITELLA PLANIGYRATA Guppy 



Plate 9, figs. 1, 9 



Turritella planigyrata Guppy, Sci. Assoc. Trinidad Proc, vol. 1, pt. 3, pp. 169- 



170, 1867, (described). 

 Turritella planigyrata Guppy, Geol. Mag. London, vol. 1, n. s., p. 408, pi. 18, fig. 



5, 1874 (very poor figure). 



