1896.] NATURAL SCIENCES OF PHILADELPHIA. 847 



The transition to marginals is extremely gradual ; the latter being 

 at first as described above (fig. 5, at 24, 25, 46), but about 20 at the 

 outer edge of radula are of the form shown in fig. 6, with distinct ecto- 

 cones, and the short, Helicid form of basal plates of other J^rtomV/oE. 



Genitalia (PI. XIV, fig. 14) somewhat as in J.. Columhianns. The 

 $ and 9 orifices are, as Binney has remarked, hardly united in an 

 atrium (see figure). The penis is fleshy, with plicate inner walls, 

 and its retractor is short and fleshy, as in Columbianus, but is ex- 

 tremely broad. The epiphallus (e/>i) is very stout, nearly as large 

 in calibre as the penis in sexually mature specimens. Further 

 downward it becomes very small again, approaches the penis, follows 

 it to its apex, turns in (fig. 15, enlarged view of apex of penis) and 

 is introverted and invaginated therein for some distance, nearly as 

 far as the insertion of retractor muscle (fig. 16, distal end of penis 

 opened, showing the invaginated epiphallus).® 



The female organs are as usual, except that there is a broad, stout, 

 fleshy vaginal retractor muscle inserted near the base of vagina.' 



It will be seen that this species shows a less advanced stage of 

 penis structure than A. Columbianus, although of the same kind. 

 The very stout, low, vaginal retractor is also a diagnostic feature. 



INSUFFICIENTLY KNOWN ARIOLIMACES. 



Ariolimax Columbiana var. Hecoxl Wetherby (Some Notes on 

 American Land Shells, p. 6) from Santa Cruz, California, is stated 

 by Wetherby to diflfer from A. Columbianus in the geuitalia, but no 

 characters whatever of the new form are mentioned. Binney 

 (Manual American Land Sh., p. 103) apparently endorses the spe- 

 cific value of the form ; but beyond stating that it has about 60.1.60 

 teeth {Columbianus varying fz'om 56.1.56 to 67.1.67), with about 16 

 laterals, he gives no characters. The form has been mentioned in 

 various lists, etc., by Cockerell and the senior author of this paper, 

 but in the entire absence of diagnosis it can have no standing, and 

 had better be dropped until described. We have not seen specimens, 

 nor, in fact, any specimens of the genus from Santa Cruz. 



Ariolimax Costaricensis CockereW, Annals and Mag. Nat. Hist. (6), 

 VI, 1890, p. 279, described as a sub-species of A. Californicus, from 



^ The slender distal end of the penis has been erroneously described as a " fla- 

 gellum" by Binney, " Blindschlaucli " by Simroth ; both overlooking the fact 

 that the epiphallus runs up to its apex, as shown in our figure 15. 



'Binney (Man. Amer. Land Sh., p. 100) calls the structure a "vaginal 

 prostate," overlooking the easily ascertainable fact that it is composed of solid 

 muscular tissue, similar to that of the penis retractor. All Ariolimaces have 

 vaginal retractors, and at times invert and protrude the vaghia, like a penis. 



