1898.] NATURAL SCIENCES OF PHILADELPHIA. 245 



Key to species of Prophysaon (alcoholic specimens). 



a. Surface with coarse diamond-meshed reticulation, the meshes 

 finely subdivided ; mantle banded or spotted ; foot-margin 

 moderate or wide. 



b. Mantle free about two-thirds of the distance back to 

 breathing orifice (PI. X, fig. 17). Epiphallus stout, 

 cylindrical, bluntly rounded at both ends; vas deferens 

 extremely long, convoluted in a snarl; usually a pale 

 dorsal line on the tail ; jaw coarsely ribbed. 



c. Outer lateral and inner marginal teeth with blunt 

 and rather short cusps. Length 50-80 mm. (in 

 alcohol), the posterior third or more being marked 

 off* by an oblique constriction and subject to self- 

 amputation, P. folio latum. 



c'. Outer lateral and inner marginal teeeth with long, 

 acutely pointed cusps. Length 25-35 mm. (in 

 alcohol), the posterior part subject to amputation 



shorter, P. Andersoni. 



b'. Mantle free as far back as the breathing orifice (PI. X, 

 fig. 27). Epiphallus slender, gradually tapering distally ; 

 vas deferens not elongated ; back with a wide red or pale 

 area enclosing a darker median band, and bounded on 

 each side by dark lateral bands, or entire slug dusky; 

 jaw closely, finely plaited or striated, 



P. humile and var. fasciatum. 



a'. Surface longitudinally closely grooved above, obliquely and 



less closely so at the sides, the grooves occasionally joined by 



short transverse lines ; foot- margin very narrow, P. cozruleum. 



P. Andersoni (J. G. Cooper). PI. X, figs. 18-22 ; PI. XI, fig. 28, 29 , PL XIII, figs. 



59-62; PL XVI, figs. 92, 93. 



Arion ? Andersonii J . G. Cooper, Proc. Acad. Nat. Sci., Phila., 1872, p. 148, 

 pi. 3, f. F, 1-5. 



Not "Prophysaon Andersoni J '. G. Cooper," W G. Binney, Second Supple- 

 ment to T. M., V, p. 42 (= P. fasciatum). 



Prophysaon Andersoni J. G. Cooper, W. G. Binney, Third Supplement to 

 Terr. Moll., V, p. 208, pi. iii, f. 1, pi. vii, f. C; pi. i, f. 3 (dentition), pi. ix, 

 f. I, J (surface reticulation). Fourth Supplement, p. 179. 



Prophysaon Andersoni J. G. Cooper, Proc. Amer. Philos. Soc, 1879, p. 288. 

 Cockerell, Ann. Mag. N. H. (6), VI, p. 278; Nautilus XI, p. 77, 78 (includes 

 P. Hemphilli). Raymond, Nautilus IV, p. 6. 



Prophysaon Andersoni var. tnarmoratum CklL, The Conchologist II, p. 72. 



P. Andersoni var '. suffusum CklL, The Conchologist II, p. 118. 



Prophysaon Hemphilli Bland & Binn., Ann. Lye. N. H. of N. Y., X, p. 295, 

 pi. xiii, exclusive of fig. 5 (external view, shell, jaw, teeth, digestive system and 



