287 Dominican Fossils — Maury 123 



whorls thirteen, the first five with two strong spirals cut into 

 coarse granules by the longitudinal ribs, on the following whorls 

 a third spiral appears between the two and on the later whorls 

 becomes equally strong; the last volution has a peripheral spiral 

 and two less strongly beaded basal spirals; ribs straight, twenty- 

 one on the last whorl extending from the umbilical region across 

 the spirals to the suture, forming square pits between the spi- 

 rals and ribs; aperture large, round; outer lip thin, flaring, 

 with a trace of a posterior sinus; anterior canal tubular, closed. 

 Length 9.5, width 2.25 mm. 



Genus Cerithium Adanson 

 Cerithium microlineatum Gabb 

 Plate 22, Figure 1 

 Cerithium microlineatum Gabb, Trans. Amer. Phil. Soc, vol. 15, p. 



236, 1873. 



This unfigured species has heretofore only been recorded by 

 Gabb. 



Localities. — (Exp'd '16) Zone D (Abundant), Zone E 

 (Rare), Rio Gurabo near Los Ouemados. 



Cerithium Russelli, n. sp. 

 Plate 22, Figures 2, 3 



Shell with many whorls carinated by a row of tubercles be- 

 neath the sub-sutural sulcus; upper whorls with two narrow, 

 well-defined varices, obsolete on the penultimate but represented 

 on the ultimate whorl by one large, irregularly rounded varix ; 

 the first five whorls following the protoconch are ribbed, the 

 riblets then break up into a larger and a smaller row of tubercles 

 separated by the sub-sutural sulcus; entire surface of the shell 

 sculptured with narrow, spiral cords; inner lip with a thick cal- 

 lus and one posterior, elongated tooth; outer lip smooth within. 

 Length of decollate shell 44, width 16 mm. 



This species is like C. microlineatum in size but distinguished 

 by its broader form and convex whorls carinated by the main 



