1905.] NATURAL SCIENCES OF PHILADELPHIA. 255 



Generic Characters of Sonorella. 



The genitalia (PI. XX) show no accessory organs on the female side. 

 The vagina is long ; the spermatheca is globular or ovate on a very long 

 slender branchless duct. The atrium is always extremely short. The 

 penis is a well-developed, thin-walled tube, containing a large papilla, 

 and terminating in a well-developed epiphallus. There is always a loose 

 sheath or wide collar enveloping the base of the penis, and attached 

 by muscular threads to the end of the epiphallus, which is thus held 

 loosely in a reflexed position. This sheath has been removed in most 

 of my figiu-es, as it obscures the parts enveloped. 



The retractor muscle is attached to the epiphallus close to the penis, 

 and is adnate to or envelops it to the apex of the latter. The fia- 

 gellum is extremely short, or even absent. The details of structure 

 are much vai'ied in the several species as described below under each 

 specific caption, and in the table of measurements. 



The free muscles, pallial complex and digestive tract have been de- 

 scribed in these Proceedings for 1900, p. 558. No material differences 

 have been observed in additional species examined. 



The jaw has four to eight ribs grouped in the median part, and either 

 strong or weak, as in the Californian Helices (PI. XXIII, figs. 18-23). 



The radula has imicuspid middle and lateral teeth, iDicuspid transi- 

 tional and inner marginal teeth and low, wide marginals with both 

 cusps bifid. Exactly the same type of teeth occurs in the Californian 

 Epiphragmophoras, in Ashmunella, Polygyra, etc. 



The upper surface of the foot is densely pebble-granose, with rather 

 indistinct dorsal grooves; the genital furrow is undeveloped except 

 near the mantle. The tail is depressed, rather long, and sometimes has 

 a weak median impressed line along the top. 



In my original diagnosis of Sonorella I stated that the shell was 

 "neither malleate nor spirally striate," Mr, Bartsch has also asserted 

 that "incised spiral lines are never present in this genus." This state- 

 ment must now be withdrawn, since several forms discovered by Mr. 

 Ferriss show impressed spiral lines; but they are inconspicuous, and 

 visible only under the lens.* To the eye, the shells of all known Sonorel- 

 las appear nearly smooth, the sculpture, aside from slight growth- 

 wrinkles, being microscopic. This is somewhat remarkable because 

 they often live in the same rock-piles with rudely sculptiu-ed Oreohelices. 



*Mr. Bartsch has excluded Helix carpenteri Newc. from Sonorella on account 

 of its spiral sculpture; but since I have found that this is not a diagnostic 

 character of the genus, I am* disposed, pending an examination of the soft 

 anatomy, to adhere to my former opinion that carpenteri belongs to Sonorella. 



