io8 Bulletin 29 272 



whorls perfectly preserved and they correspond to Brown's and 

 Pilbry's description of the protoconch of D. gatunensis. 



Gabb notes the resemblance of the Dominican fossil Distor- 

 trix to the West Coast D. constrirta; but it is much more like 

 specimens from St. Thomas, W. I., labelled by Dr. Newcomb 

 ridens Reeve. 



Localities. — (Exp'd '16) Zones A, B, D, E, Rio Gurabo at 

 Los Quemados; Bluff 1, Cercado de Mao. (Very large and abun- 

 dant). 



Genus Bursa Bolten 



Bursa crassa Dillwyn 



Plate 17, Figure 6, 7 



Ranella crassa Dillwyn, Reeve, Icon., fig. 18, b. 



Ranella crassa Guppy, Quart. Jour. Geol. Soc., London, vol. 22, p. 288, 



pi. 18, fig. 9, 1866. 

 Bursa crassa Gabb, Trans. Amer. Phil. Soc, vol. 15, p. 212, 1873. 

 Ranella crassa Guppy, Geol. Mag. London, p. 438, 1874; Quart. Jour. 



Geol. Soc., vol. 32, p. 522, 1876. 

 Gyrineum crassum Dall, Trans. Wagner Inst. Sci. , vol. 3, pt. 6, p. 



1584, 1903. 



This species is still living on unchanged in the Antilles. It 

 occurs as a fossil at Bowden and in Santo Domingo. 



Localities. — (Exp'd '16) Rio Cana, Guayubin to Mao road, 

 and Cerro Gordo to Mao road. 



Bursa bufoniopsis, n. sp. 

 Plate 17, Figure 8 

 Shell somewhat flattened dorso-ventrally, whorls seven, the 

 first two nuclear, subsequent volutions with two lateral varices 

 each; varices rounded, their sculpture corresponding to the spiral 

 ornamentation of the shell but rather more pronounced; intervari- 

 cal tubercles three, often with a fourth, weaker tubercle on the 

 dorsal side of the last two whorls; body whorl on the dorsal sur- 

 face showing about nine spirals of which the uppermost is nodu- 

 lar, the second, third, fifth, seventh and ninth are single, beaded, 

 the fourth, sixth and eighth are paired, beaded. Aperture oval, 

 outer lip slightly reflexed, fluted, bearing nine interrupted denti- 



