1911.] NATURAL SCIENCES OF PHILADELPHIA. 469 



NOTES ON THE ANATOMY AND CLASSIFICATION OF THE GENERA 

 OMPHALINA AND MESOMPHIX. 



BY HENRY A. PILSBRY. 



In the course of studies on the shells of large Zonitidce of the 

 Southern States Mr. George H. Clapp reached the conclusion that 

 the species referred to Omphalina are divisible into two generic- 

 groups, one having 'the embryonic whorls of the shell smooth, the 

 other having these whorls radially costulate or sharply striate. 

 His results being communicated to me, an anatomical study of all 

 the species was undertaken. I found that two genera are clearly 

 indicated by the soft anatomy and that these coincide with the 

 groups based upon the sculpture of the embryonic shells, except 

 that the species inornata Say and andrewsce Pils. have smooth embryos, 

 yet their soft anatomy is like the group with striate embryos. 



Hoping to find time for a revision of the species with full illustra- 

 tion of the shells, I laid aside the notes made in 1905-6; but as 

 opportunity for the preparation of adequate illustrations of the 

 shells has not appeared, the anatomical and taxonomic data are now 

 published. 



W. G. Binney, in the Terrestrial Mollusks, vol. V, has figured the 

 genitalia of inornata (PI. XI, fig. C), friabilis (fig. D.) and laevigata 

 (fig. E). In the latter figure the penis is lettered d.s., and its flagelli- 

 form gland and retractor, or both, marked r. Omphalina friabilis 

 is figured with a vaginal gland marked p.p. The fact is that Binney 

 took the distal end of the penis for an appendage or dart-sack, and 

 did not recognize the true nature of the epiphallus. The resulting 

 inaccuracy of the figures and descriptions deprives them of value. 

 He has, however, done much useful work on the dentition, the 

 shell-characters, and in the elucidation of the older species, the 

 synonymy of which had become intricate. 



Genus OMPHALINA Rafinesque. 



It is proposed to restrict this genus to species having the embryonic 

 whorls of the shell smooth, and the penial retractor muscle terminal 

 on the penis, which does not extend beyond it in a flagelliform blind 

 sac. The type is 0. cuprea Rafinesque (fuliginosa " Griffith " Binney) . 



