1892.] NATURAL SCIENCES OF PHILADELPHIA. 215 



The jaw of this species has been figured as smooth by Binney, but 

 as that examined by me difl^ers in having about seven low, unequal, 

 rounded ribs, I have deemed it best to figure it for comparison (fig. 

 J.). It is likely that there is considerable variation in this organ, 

 some closely allied species having a strongly ribbed jaw, others a 

 smooth jaw, as Binney has demonstrated. 



The sole is indistinctly tripartite. 



The genitalia are intermediate between those of Lucerna and 

 Caracolus s. str. The penis has a short flagellate extension beyond 

 the insertion of the vas deferens (fig. I,/.). The spermatheca duct 

 is long (sp.) 



The genitalia of Caracolus, Lucerna, Dentellaria and Thelidomus 

 have proved that the reference of all these large, opaque Helices of 

 tropical America to a single genus (^Caracolus) is a natural arrange- 

 ment. The classification proposed by me in 1889', mainly npon 

 conchologic characters, will therefore stand. It is safe to predict 

 that the South American sections Lahyrinthus and Isomeria will 

 prove to be essentially similar to Lucerna and Dentellaria in 

 anatomy. 



Explanation of Plate XIII. 



Fig. A. Genitalia of Sagda similis, showing the penis and the lower portion of 

 the female system, p. penis; r. p. retractor muscle of the penis ;_/?. 

 flagellum; 2. o. accessory organ of the penis; v. d. vas deferens. 



Fig. B. View of the lower portion of the penis with its accessory organ, the latter 

 partially pinned out. Lettering as in fig. A. 



Fig. C. Female genital organs of Sagda similis. At 0. are seen eggs in the ovi- 

 duct. 



Fig. D. Jaw of Sagda similis. 



Fig. E. Foot of Sagda similis. t. tail, showing granulation, s. sole showing the 

 median furrow. 



Fig. F. Genital system of Cysticopsis tenerrima Ad, /. penis ;y?. flagellum ; r. p. 

 retractor muscle; v. d. vas deferens x. x. flagellate extensions of the 

 accessory organ of penis ; g. cl. genital cloaca; sp. spermatheca; a. gl. 

 albumen gland ; h. d. hermaphrodite duct. 



Fig. G. Teeth of Aegista platyottiphala Mlldff". 



Fig. H. Jaw oi Aegista platyompkala Mlldff". 



Fig. I. Genitalia of Denlellaria orbiculata Fer. Lettering as in Fig. F. 



^^Z- J- Jaw of Dentellaria orbiculata Fer. 



^ Manual of Conchology, 2d Series, V, p. 75, 76. 



