HELIX. 335 



H. desertorum Forsk., iv, 127, H. desertorum. 



[261. v. hasselquisti Ehr. 



macufosa Born. /. ehrenbergi Roth. 



irregular is Fer. chilembia Bgt. 



forskalii Ehr. v. hemprichi Ehr. 



arabica Roth. v. aschersoni Reinh. 



psamitus Bgt. H. desertella Jick., iv, 127. 



gemellarii Ben. H. duroi Hid., iv, 128. 

 rhodia Chemn. /. minor Kob., iv, 261. 



depressa Mts. haploa West. 



pachytoichea West. 

 kobelti West. 

 dillwyniana Pfr. 



Subgenus EUPARYPHA Hartraaun, 1842. 



Euparypha HARTM., Erd.- u. Siisswasser Gasterop. Schw., p. 204, 

 for H. rhodostoma =pisana. Conf. for anatomy, SCHMIDT, Sty- 

 loiumat., p. 22. pi. 5, f. 23 ; MOQ.-TAND., Moll. Fr,, p. 259, pi. 19, f. 

 9-19, SCHUBERTH, Arch. f. Naturg., 1892, p. 55, pi. 6,f. 1-3. 



Shell narrowly umbilicate or subimperforate, compact, solid, creta- 

 ceous, subglobose or depressed and keeled, white or light, usually 

 decorated with many dark irregularly placed bands and lines. Sur- 

 face striated, the striae decussated by spiral incised lines, at least on 

 the spire. Suture superficial; last whorl descending or straight; 

 aperture little oblique, lunate, the lip sharp, not expanded, thickened 

 by an internal callus rib, columellar end triangularly reflexed. 

 Type H. piscina, pi. 43, figs. 37, 38. 



Jaw well arched, with two or three strong ribs denticulating both 

 margins. Radula as in Pentatsenia, Helicigona, etc. ; the middle 

 cusp of middle tooth is longer than the short, square basal plate, 

 side cusps small ; laterals similar but without inner cusp, outer cusp 

 larger; marginals with a long bifid inner cusp and smaller outer 

 cusp, the latter split on the outer teeth. 



Genital system (pi. 61, figs. 1,2, 3, 4, 5, H.pisana) characterized 

 by the lack of flagellum on penis, the retractor and vas deferens ter- 

 minal ; sperm atheca duct long, without a diverticultim (or accord- 

 ing to Schmidt with a short one) ; mucus glands two, long, simple 

 and tubular. Dart sack small, containing a straight, four-edged, 

 coronated dart (fig. 2, 4, 5) like that of Tachea splendida. 



