308 HELICIGONA. 



sist of short lobes, somewhat as in Eulota ; but unlike that genus, 

 they are inserted on vagina well above the dart sack, so there can be 

 no doubt that they are merely a shortened form of the finger-like 

 glands characteristic of Belogona Siphonadeuia. 



H. quimperiana Fer., iv, 116. Brittany; Spain. 

 kermorvani Coll. 

 corisopitensis Dh. 



Subgenus ISOGNOMOSTOMA Fitziuger, 1833. 



Isognomostoma FITZ., Syst. Verzeichniss der in Erzherzogthume 

 Oesterreich vorkommenden Weichthiere, p. 97, sole species, I.per- 

 sonatum Eitz., =H. personata Drap. Isognomonostoma TRYON 

 Triodopsis of modern European authors, not of Rafinesque! 

 Plicostoma SCHLUTER, Syst. Verz., 4, 1838. See for anatomy Schu- 

 berth, Archiv f. Naturg., 1892, p. 11, pi. 1, f. 15-18 (Good!) 



Shell depressed-globose, with low convex spire, narrow or closed 

 umbilicus and rounded or faintly angular periphery ; surface smooth, 

 hirsute in quiucuncial pattern. Aperture oblique, ear shaped ; 

 peristome flatly reflexed, thickened within, toothed on outer and basal 

 margins; terminations connected by a raised, tongue-like parietal 

 process. Type H. personata, pi. 43, figs. 31, 32. 



Jaw with about 5 strong ribs, dentating the cutting margin ; 

 radula with large triangular mesocones on middle and inner lateral 

 teeth ; marginals with a bifid inner and simple outer cusp. Genital 

 system (pi. 62, fig. 19, H. personata) with penis as usual in the genus; 

 2 long mucus glands; an elongated dart sack containing a dart 

 of typical Helicigone form, base dilated, shaft slender and round, 

 spreading into a two-bladed, laurel-leaf shaped head. Diverticulum 

 bound to uterus by a broad membrane, as usual in Helicigona. 



Distribution, middle Europe and Siberia. 



The anatomy of this group is typical of Helicigona (Campy I ceo), 

 having the diverticulum membrane found in that genus only, (re- 

 moved in the figure), as well as the characteristic form of mucus 

 glands and dart. These features of the genital system, as well as 

 the strongly ribbed jaw, show that the association of H. personata 

 with " Gouostoma " is entirely illusory. In fact Schuberth, in his 

 anatomical characterization of "Anchistoma" (" Gonostoma"-f 

 " Triodopsis ") was obliged to make an exception of H. personata^ 



