[8i Dominican Fossil^ — Maury 17 



Shell minute, sub-cylindrical, anterior end rounded, marked 

 by a few faint, fine striae, posterior end sharply and conspicuous- 

 ly pointed; aperture linear, widening anteriorly, inner lip slightly 

 thickened at the base and refiexed. Length of shell 4 mm., 

 greatest width 1.5 mm. 



Dr. Dall notes that this species is identical with Miss Bush's 

 recent species Volvula oxytata, now living from Hatteras to Cape 

 Fear and reported doubtfully from the West Indies. To a less 

 degree it resembles the Cuban recent shell, Volvula acuta d'Or- 

 bigny, which is broader and less cylindrical in form. 



V. cylindrica was found by Dall in the Bowden beds, Ja- 

 maica. The type locality is Santo Domingo. Guppy also iden- 

 tified it in Heneken's collection from the Yaqui Valley. 



Localities. — (Exp'd '16) Bluff 2, Cercado de Mao (very 

 rare); Bluff 3, Cercado (very abundant); Zone I, Rio Cana 

 (scarce). 



Genus Retusa Brown 



Retusa yaquensis, n. sp. 



Plate 3, Figure 6 



Shell small, sub-cylindrical, broadening slightly anteriorly, 

 not constricted near the middle; minutely perforate; spire sunken, 

 umbilicate; outer lip elevated posteriorly above the spire, its 

 margin forming a U-shaped upward curve, then it becomes a 

 trifle inflected along the center, and slightly produced anteriorly ; 

 inner lip thickened anteriorly and reflected over the umbilical re- 

 gion; pillar with a single plication; anterior end of the shell 

 sculptured by about half a dozen faint, wavy, unequal spiral 

 lines; posterior end similarly sculptured with about twice as 

 many spirals extending a varying distance up towards the center 

 of the whorl. Length of shell 3.50, greatest width 1.50. 



This appears to be the first Retusa found in the blue clays 

 of Santo Domingo. It is rather scarce. 



Localities. — (Exp'd '16) Bluff 3, Cercado de Mao (one speci- 

 men); Zone H, Rio Cana (six specimens). 



