470 PROCEEDINGS OF THE ACADEMY OF [July, 



The Mexican species lucubrata Say (PL XXXVII, fig. 8, genitalia), 

 caduca Pfr., zonites Pfr., belong to this genus. Zonyalina (jal- 

 apensis) and Patulopsis (carinata), according to Strebel's figures, 

 are very closely related and might be retained as subgenera of Ompha- 

 lina, as von Martens has done. 



Both Omphalina and Mesomphix have a collar-like gland, usually 

 chocolate-colored, around the base of the vagina. A similar gland 

 has been noticed in Zonites algirus, Zonitoides nitida and excavata, 

 Rhysota brookei, etc. Its apparent absence in some dissections may 

 be due to imperfect preparation or to imperfect development or 

 pigmentation. The external features of the soft parts are similar 

 in the two genera. In both the orifice of the genitalia is posterior, 

 under the pneumostome, as shown in fig. 2 C. 



The dentition is not greatly varied in the Omphalinas of the 

 United States and probably the radulse of 0. pilsbryi, 0. cuprea and 

 0. friabilis could not always be distinguished. 0. kopnodes has 

 more lateral teeth than the other species. The number of teeth in 

 radulse counted is as follows: 



Central. Lateral. Marginal. 



0. kopnodes 1 7 66 Huntsville, Ala. 



1 9 57 (Binney). 



0. pilsbryi 1 5 or 6 49 or 50 Wetumpka, Ala. 



0. cuprea 1 5 54 Emporium. Pa. 



" 1 5 45 Pennsylvania. 



" 1 4 60 (Binney). 



0. c. ozarkensis 1 6 54 Magazine Mt., Ark. 



O. friabilis 1 7 54 Wyandotte, I. T. (immature). 



1 5 65 San Marcos, Tex. 



1 5 55 Mablevale, Ark. 



1 6 51 (Binney). 



a 



The position of the epiphallus on the penis is a character of impor- 

 tance in distinguishing species, but it fails with immature indi- 

 viduals, in which the epiphallus is probably always inserted very 

 near the end of the penis. The "swollen" or "slender" shape of 

 penis and epiphallus is variable individually, and probably related 

 to functional activity. The measurements of the organs in speci- 

 mens figured follow: 



Length of kopnodes. cuprea. pilsbryi. friabilis. friabilis. 



(Mablevale.) (San Marcos.) 



Penis 10.5 12 9 5 6 



Epiphallus 21 15.5 16 5.5 15 



Vagina 7.5 6 4 8.5 



Spermatheca and its 



duct 19 15 11 8 13.5 



A Miocene species, O. laminarum, has been described by Professor 



