LOCALLY INTRODUCED SPECIES. 469 



from Charlestou, S. C, placed in my garden at the same time, disap- 

 peared at once. 



The jaw of a Burlington specimen of nemoralis is very strongly arched, 

 with 4 stout ribs on its anterior surface, denticulating each margin. 



For lingual membrane and jaw of T. hortensis see above, pp. 466, 467. 



The genitalia of the European T. hortensis is figured by Schmidt (Ge- 

 schlechts. der Stylomm., Plate III, Fig. 15). The genital bladder is 

 small, globular, on a very long and delicate duct, to which is a short 

 accessory duct. The penis sac is long, cylindrical, tapering above the 

 insertion of the retractor muscle to the point where the vas deferens 

 enters, beyond which it has a long, flagellate extension. About half 

 way between the end of the duct of the genital bladder and the common 

 orifice is an elongate-ovate dart sac, from the base of which, on either 

 side, is a bundle of greatly developed multifid vesicles, each composed 

 in the specimen figured of four long caeca. 



POITIATIA (Leach), Beck. 



Animal heliciform ; mantle subcentral ; other characters as in Pa- 

 tula. 



Shell imperforate or subimperforate, globose, striate, horny- calcare- 

 ous, generally banded ; whorls 4-6, convex, the last large, ventricose, 

 descending 5 aperture lunate-orbicular ; peristome patulous or straight, 

 within labiate with callus, the columellar margin reflected, generally 

 callous. 



Foundaround the Mediterranean Sea; a few species found elsewhere — 

 Mexico, Japan, &c. One species only introduced by commerce within 

 our limits. 



Jaw of our only species, P. aspersa, introduced by commerce at Charles- 

 ton, S. C. (where it is still common), high, thick, arcuate; ends but little 

 attenuated, blunt; cutting margin without median projection; anterior 

 surface with 6 stout, separated ribs, deeply denticulating either margin 

 (see Fig. 513). Lingual membrane of the same species (Terr. Moll., V, 

 Plate X, Fig. D) long and narrow. Teeth 50-1-50, fig. 513. 



with 15 perfect laterals. Centrals with base of at- 

 tachment longer than wide, the lower lateral angles 

 but slightly produced, the lower margin in some 

 cases with a quadrate excavation or thinning, as 

 usually found in Succinea, the upper margin broadly Jaw of p. aspersa. 

 reflected, reflection very large, with a very stout, short median cusp, 



