260 NEW YORK STATE MUSEUM 



InPolygyra profunda the base of the penis is included 

 in a sheath formed by a continuation of a part of the genital 

 chamber, in the form of an inverted cone. In C i r c i n a r i a 

 concava it is long and cleft or bipartite at the summit. 



The lining membrane usually has a number of rugae, longitudi- 

 nal and oblique. Sometimes^ as in P. a 1 b o 1 a b r i s and P y r a- 

 midula alternata, there is one very large fold. In many 

 species, as in P. a 1 b o 1 a b r i s, the surface of the membrane is 

 papillated, but in some others it is smooth. 



The vagina and, receptaculum seminis vary in form. In the 

 greater number of species the vagina is not as large and muscular 

 as in P. a 1 b 1 a b r i s, and the duct leading to the receptaculum 

 seminis is generally longer. 



In Helix aspera and other European species there are 

 several accessory organs not found in P. a 1 b o 1 a b r i s or in 

 L i m a X. They are the flagellum^ the dart sac and the accessory 

 mucous or digitate glands. 



The flagellum is an elongated diverticulum of the penis and is 

 much coiled. The dart sac is an elongated, clavate, appendage 

 from the base of the oviduct. It has powerful muscular walls, 

 and contains in its interior the dart or spieulum amoris, attached 

 to a nipple-like protuberance at the bottom of the sac. The dart is 

 four-bladed, calcareous, and growing by the addition of calcare- 

 ous particles^ deposited at its base from the vascular protuberance 

 to which it is affixed. If broken off it is speedily renewed in like 

 manner. Before coition the dart sac is everted from the genital 

 orifice, the dart thus becoming exposed. It is probably an excita- 

 tory organ. 



The mucous or digitate glands, according to T. Rymer Jones, 

 ^' consist of a series of branched ceca, derived from two excretory 

 ducts, by which a milky fluid, secreted by the ceca, is poured into 

 the egg passage prior to its termination ". , 



The receptaculum seminis of Helix aspera differs 

 greatly from that of P. albolabris and L i m a x m a x i- 

 m u s, consisting of an elongated duct, which subdivides into two 



