18 L'niicrsily of Michigan 



Height ^laj.Diam. ^lin. Diam. 



180 (.18.0) 140 (14.0) von Martens (1873). 



175 (14-0) 137 (16.0) 



164 C18.0) 145 (16.0) A. J. Wagner (1905). 



192 (17.1) 160 (14.2) Puerto Cabello. 



167 (16.0) 147 (14.1) Ci. infesta. 



200 CI4-4) 165 (11.9) San Esteban. 



196 (15.7) 166 (13.3) 

 200 (,150) 167 (12.5) 

 187 (15.9) 160 (13.6) 

 185 (13-7) 160 (11.8) Boqueron. 



197 (16.9) 166 (14.3) 



This form has often been confused with H. caiidcaiia Sow- 

 erby (1842), from Honduras. After comparison of the de- 

 scription and figures v.-ith the specimens before me, H. iiifcsta 

 seems Httle more than an extreme form-variation of H. r. 

 cnicsti. Other species from northern South America are : H. 

 rhynchostouia rhyiichosfoimi "Shuttleworth" Pfr. (1865) from 

 Campanera, Colombia (L ???); H. ocaiiciisis A. J. Wagner 

 (1905) from Ocana. Colombia (L 8. Jt,); H. stcindachucri 

 and the cotypical form siipcrstritcta A. J. Wagner (1905) from 

 Frontino. Colombia ( L 7, //) ; H. colombiuc E. A. Smith 

 (1878) from San Sebastian, Xew Granada (L n. 74"'> : and 

 H. gonochila Pfr. (1849) {-\-gonochcila Sowerby. 1874) from 

 Venezuela (Caracas?). I have seen no authentic specimens of 

 any of them. but. from descriptions and figures, the second ap- 

 pears to be quite distinct, the third rather close to H. rhyncho- 

 stoma; the fourth is unfigured. but seems to differ from the 

 first by its smaller size and higher spire. H. gonochila closely 

 resembles H. bracilicnsis Gray (1824). and its Venezuelan hab- 

 itat appears open to doubt. 



The radular formulae of H. r. cmcsti and H . caracoUa are 

 given in another paper (1922) ; examples of the teeth are fig- 

 ured here (figs. iv-i6. 18). 



