406 



TERRESTRIAL AIR-BREATIIING MOLLUSKS. 



and as long as the oviduct; the vagina is broad and muscular; at the base of 

 the penis there opens a short, cylindrical duct, derived from a single raultifid 

 vesicle, which presents six or seven rounded or ovate divisions ; there is no 

 dart sac. 



ORTHALICUS, Beck. 

 Animal (see below). 



Shell imperforate, ovate or oblong, ornamented with of\en articulated fillets ; 

 apex obtuse, last whorl inflated ; columella uniformly thickened, sometimes 

 callous, arcuate, obliquely subtruncate at base ; aperture longitudinal, oval. 



The genus Oiihalicus does not properly belong to the fauna of North Amer- 

 ica, but rather to that of tropical America, from whence specimens have been 

 introduced to the Florida mainland and keys, and Jamaica. In what manner 

 it was introduced it is difficult to say (see p. 36). 



Subgenus ORTHALICUS, Bkck, s. str. 



Animal heliciform, large, scarcely included in the shell, long and obtuse 

 before, rapidly attenuated behind ; mantle posterior, slightly overlapping the 



Fig. 284. 



Animal of O. vnda'.us. 



peristome of the shell, and bilobed ; respiratory and anal orifices under the 

 peristome; orifice of generative organs behind the right eye-peduncle; no 

 caudal mucus pore, no locomotive disk. 



Shell imperforate, ovate or oblong-conic, thin, striated, decussated with curl- 

 ing lines, and ornamented with usually articulated fillets and oblique swaths ; 

 whorls 6-8, the last inflated ; columella filiform, loosely arcuated-intorted, 

 obliquely subtruncated at base; aperture oval; peristome straight, its margins 

 connected by a light callus. 



The jaw of the only species within our limits, O.undatus, Brug. (see Fig. 285) 

 is of the type usual in this genus and Lir/iius (see Fig. 283), but up to the pres- 

 ent time never observed in any other genus. It is composite, its separate pieces 

 being apparently soldered firmly at their upper portions, where, indeed, they 

 seem collectively to form a jaw in a single piece, as in Patula, etc., but at their 



