54 PKOCEEDINGS OF THE NATIONAL MUSEUM vol.66 



broken oft". Shell of medium size and solid; whorls loosely coiled, 

 medially concave, and rapidly enlarging in ascending -the spire. 

 Suture deep. Spiral sculpture on the early whorls of two low, 

 weakly nodulous cords bordering the upper and lower shoulder of 

 the whorl and separated by a shallow, broadly rounded concayity 

 marked within with two smaller, weakly nodulous spiral cords. 

 Lower spire whorls spirally sculptured with two moderately high 

 cords serrated at their summits and occupying the upper and lower 

 third of the whorl; these cords are separated by a broad, shallow 

 concayity marked with two secondary spirals. The upper primary 

 spiral weakly coronates the whorl. Another low spiral lies behind 

 the suture and forms behind it on the basal slope a narrow and 

 shallow sulcus which becomes more prominent on the body whorl. 

 On the body whorl, the two primaiy spirals are low and rounded and 

 the median band is shallow; the surface is roughened by imbricated, 

 flexuous growth structures which almost conceal the median spirals. 



Dimensions: Larger cotype (U. S. Nat. Mus. Cat. No. 352682) 

 measures: Length 39 mm.; greatest diameter 15 mm. 



The new species resembles Turritella altilira costaricensis Olsson 

 from Gatun formation. Upper Hone and Boucary Creeks, Costa Rica, 

 but the primary spirals on Olsson's species are weaker than on tlie 

 new species. 



Occurrence. — Caroni County, Montserrat Ward, junction of Gran- 

 Couva and Brasso-Tabaquite Roads. 



TURRITELLA, species cf. T. ALTILIRA, var. CHIRIQUIENSIS Olsson 



Plate 10, figs. 2, 5 



TiirriteUa altilira chiriquiensis Olsson, Bull. Amer. Paleont., vol. 9, p. 322, 

 pi. 7, figs. 4, 8, 9, 14, 1922. 



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

 no. 42, p. 230, pi. 42, figs. 4, 5. (Not Turritella tornata Guppy.) 



The form compared with this variety in our collection consists 

 either of young individuals or fragments of the lower whorl of adult 

 specimens. It differs mainly from 7'urrltella altilira (typical) in 

 being a slightly less attenuated shell and having more delicate sculp- 

 ture ornamentations, and spiral sculpture markings on the upper 

 slope of the posterior spiral cord. Of all specimens of Tm^ritella 

 oltilira examined, the sunnnit of the posterior spiral cord on the 

 adult whorls is posteriorly reflected and the presutural area in front 

 of it is very weakly spirally sculptured or bare. The lower member 

 of the posterior spiral when doubled is the last to appear and 

 gradually increases in strength in ascending the whorl. Some of 

 the Trinidad specimens show a double posterior spiral but the 



