HELIX. 255 



than the penis. The bottom of the tube, for one fourth the length of the 

 latter, is occupied by the papilla from which arises the dart. The muscular 

 layer, for more than half the length of the tube, at the middle of the latter 

 closely envelops the dart, and terminates abruptly below in a sort of papilla, 

 from which the point of the dart projects into the lower part of the tube. The 

 dart is usually a very long, narrow, curved, cylindrical, tubular, flexible, calca- 

 reous spiculum, terminating in a sharp spear-point. At the base of the dart 

 there opens into the dart sac, in ligerus and suppressus, a single, short, pyriform 

 follicle, the simplest homologue of the multifid vesicle. In intertextus and gularis 

 there is a pair of such follicles. Those organs, the dart sac and multifid vesicles, 

 so common in European species, are very rare in American species excepting 

 Arionta, which also usually has the flagellate form of penis. A rudiment, or 

 simplest condition of the multifid vesicles, only exists in intertextus and 

 gularis, in which there is a single pair of follicles, and ligerus and sup- 

 pressus, in which there is but one short follicle. The dart sac exists cer- 

 tainly in the four latter species, probably in Berlanderiana. In the species 

 of the West Coast now referred to Arionta, the dart sac is very common, and 

 also various complications of vaginal prostates described under each species ; 

 the duct of the genital bladder has often a long, accessory duct. 



The above summary, however imperfect, will serve to show how very vari- 

 able are the genital organs. They cannot be relied on as generic characters, 

 but are often of great value in distinguishing species. 



Doubtful, Spurious, Extralimital Species of Helix. 



The following list does not contain the names of our species of dismembered 

 Helix : — 



Helix (Sheppard, Trans. Lit. and Hist. Soc. Quebec, I. 194). — Shell thin, 



conoidal, perforated ; spire very flat ; margin of lip reflected. 



Common in the same place as the above (H. hortcnsis, Plains of Abraham, 

 Quebec) ; it is a much less shell, with a brown epidermis ; the penultimate 

 whorl has an elevated white ridge near the aperture, which appears to be some 

 remains of the last year's lip. (Sheppard.) [= //. rufescens ?] 



Helix Sagraiana, D'Orbigny, a Cuban species, is erroneously attributed to Cali- 

 fornia (on the authority of Sowerby) by Pfeiffer (Mon. I. 325) and Car- 

 penter (Report, p. 214). 



Helix Sandiegoensis, Lea, is mentioned by name only by Gould, Pac. R. R. Rep., 

 V. 331. 



Helix attenuate, Lake Superior, etc., is given without description by J. de C. 

 Sowerby, in Richardson's Fauna Boreali-Americana (III. 315), together with 



Helix gularis, 



Hili.r rudis, and 



Helix paludosus (= H. minuta). 



Helix angulata, Sheppard, is quoted as a synonyme of Planorbis campanulatus, 

 by J. de C. Sowerby, in Fauna Boreali-Americana, III. 315. 



Helix pallida, Budgin, Virginia, is quoted as a synonyme of an unnamed Helicella 

 ly G. B. Sowerby (Tankervdle Coll., 37), and 



