4 2 University uf Michigan 



41. Ouebracla La Fria, near Camino Real. 



42. Ouebrada Santa Aguita. near Camino Real. 



43. Between Ouebrada Las Pipas and Rio Oropito. 



44. The "tombas" at the railroad bridge across Rio La (Jrita. 



El Guayabo, Estado Zulia. 

 (L 8, "jz: 68 meters altitude.) 



45. Near Rio Zulia (El Caiio Fraile). 



Encontrados, Estado Zulia. 

 (L 9, 72] 42 meters altitude.) 



46. Ponds and river flats near Rio Catatumbo, northwest of 



town. 



XERITID.E 

 Xcritiua virginca rcdivata (Say). 



vSeventeen s])ecimens from slightly brackish lagoon near 

 Maracaibo (E. B. Williamson). These specimens resemble 

 closely those from Florida, although they somewhat approach 

 N. V. microstoma from Cuba. A few show more widely-spaced 

 hair-lines than is common in typical X . v. rcdivata. The gen- 

 eral coloration is dark olive-green to olive-brown. The radula 

 of specimens from this lot have been figured in another paper 

 (1Q23, Proc. Acad. Xat. vSci.. Philadelphia). Tndivi(Uials 

 measure :- 



altitude major diameter 



137 97 (^2>-Z)- 



12.2 102 (12.5). 



10.8 90 (10.7) 



- Throughout this paper, the altitude of the shells is given in milli- 

 meters. The other dimensions are expressed as an index, the dimen- 

 sion divided by the altitude, in percentages of the latter. The dimen- 

 sion index is followed by the actual measurement in millimeters (in 

 parentheses). 



