1922] NATURAL SCIENCES OF PHILADELPHIA. 57 



S. hidalgoana Ball (1897). Encarnacion, Hidalgo, Mex. ; near Victoria, Tarn., Mex. 



S. hinkleyi Pilsbry (1919). Chama, Guatemala. 



???S. minima "Pfr. " Strebel (1873). Figure only, unidentifiable. 



S. minuscula (Pfr.) (1859). Mexico. 



S. miniuscula auct. 

 S. nicoleti Shuttleworth (1852). Cordova, Mexico. 



S. palmeri Dall (1905). Alvarez Mts., San Luis Potosi; Omealca, V. C, Mex. 

 S. pannucea (Morelet) (1849). Peten, Guatemala. 



H. alata Adams (1856), not Pfr. 

 ?S. pannucea misantlensis Strebel (1873). Misantla, V. C, Mex. 

 ?S. pilsbryi A. J. Wagner (1910). Mexico, Guatemala. 

 S. vanattai Pilsbry (1899). Diente, Nuevo Leon, Mexico. 

 S. vanattai tricostata Pilsbry (1903). Near Victoria, Tamaulipas, Mex. 

 S. xanthia Pilsbry (1909). Los Canoas, San Luis Potosi, Mex. 



The radula of S. hidalgoana 39 is figured (Plate V, figs. 18 and 20). 

 The centrals are somewhat Alcadia-like; the B-central has an outer 

 projection that fits under the C-central. The comb-lateral is 

 large and heavy and has a squarish base, -but the outer triangular 

 projection is so thin and weak as to be difficult to see. The accessory 

 plate is rather small and not very heavy. The inner 9 marginals 

 are bicuspid and resemble those of Emoda, although the blades are 

 considerably longer and more close-ranked than in that group. 

 The small number (46) is striking in a shell as large as the present 

 species. 



The distinctive shell characters were noted early, and are so 

 peculiar as to probably warrant the generic separation of this 

 group and Emoda, but the writer did not wish to erect the latter 

 into a genus until a more thorough study of the West Indian forms 

 had been made. The species from the mainland of North America, 

 given above, constitute simply an alphabetic list of the names 

 that have been proposed. 



Genus STOASTOMA Adams. Jamaica. 



Stoastoma C. B. Adams (18-19). Type S. pisum C. B. Adams (1849). 



Jamaica. 

 Hemicyclostoma "C. B. Adams" Pfr. (1865). Type S. pisum. 

 ? Lewisia Chitty (1857). Type S. philippianum C. B. Adams (1850). 

 ? Wilkinsonia Chitty (1857) Type S. wilkinsoniae C. B. Adams (1849). 

 ? Fadyenia Chitty (1857). Type S. fadyenianum C. B. Adams (1849). 

 ? Metcalfeia Chitty (1857). Type 5. chittya?ium C. B. Adams (1849). 

 ? Petiiia Chitty (1857). Type S. petitianum C. B. Adams (1849). 

 ?? Lindsleya Chitty (1857). Type S. lindsleyanum C. B. Adams (1849). 40 

 ? Blandia Chitty (1857). Type S. blandianum C. B. Adams (1849). 



The radula of the type species has already been figured by Pilsbry 



39 2 dried specimens; A. N. S. P. no. 85919; collected in canon 4 miles west of 

 Victoria, Tamaulipas, Mexico, by S. N. Rhoads (1903). 



40 The second name in this list is an exact synonym of Stoastoma ; the remainder 

 may be distinct. I have already tentatively included Lindsleya under Luciddla. 



