1896.] NATURAL SCIENCES OF PHILADELPHIA. 431 



quite positively that a great proportion of this variability in this 

 instance is due quite as much to an intrinsic tendency to vary in the 

 matter of color and form as to any direct influence of the environ- 

 ment promoting by special circumstances any special variation. At 

 least, while it is not questionable that some of the variations might 

 easily be made permanent by natural selection, it is probable, as 

 yet, that matters have not reached that stage, since the evidence of 

 collectors seems to establish the fact that the different variations of 

 color and form are found indiscriminately in the same region and 

 under the same conditions. Further and more precise observation 

 is needed to establish this beyond controversy, but at present there 

 seems no escape from this conclusion. 



An examination of several specimens by Mr. Binney afforded the 

 following anatomical data : " Genitalia with a short, stout, linguiform, 

 bluntly pointed ovary ; testicle of numerous bunches of long blunt 

 cseca ; epididymis long, convoluted along nearly its whole length ; 

 oviduct long ; genital bladder small, oval, on a long stout duct ; 

 penis sac long, narrow, subcylindrical, white, with a silken lustre, 

 receiving the retractor muscle at its upper third, the vas deferens at 

 its apex." 



Jaw low, wide, ends rather blunt, but little arcuate, anterior sur- 

 face with about 20 broad, flat, crowded ribs, squarely denticulating 

 both margins. It is thin, membranaceous, light horn-colored, of 

 equal height throughout, with the outer edges of the ribs reinforced. 



Radula long and narrow, formula ^ ; rhachidian with a 



31.9+9.31 



long central and two shorter lateral cusps, the whole narrower than 

 the base ; true laterals bicuspid, the outer cusps shorter, 9 in number 

 on each side ; marginals low, wide, with one long wide bifid inner 

 cutting point and one outer short bifid cutting point, the latter in the 

 extreme marginals becoming irregularly serrate. In the figure 

 (plate XVI, fig. 6) of the genitalia, the proximal orifices are sepa- 

 rated, an accident of dissection, the two canals actually open into a 

 single atrium. 



Bulimulus (Nsesiotus) rugulosus Sowerby. Plate XYII, figure 1. 



Bulinus rtigulostis Sby., Conch. 111. Part 142, fig. 87 (a, b), 1839. 



Bulimus rugulosus Pfr., Mon. Hel. Viv., II, p. 113, 1848. 



Bulimus eschatiferus Reeve, Conch. Icon., pi. xx, fig. 121, (text, figure ex- 

 cluded), 1848, not of Sowerby. 



Bulimuluz [Omphalostyla) rugulosus H. & A. Adams, Gen. Rec. Moll., II, p. 

 161, 1855. 



