HELIX-RHAGADA. 185 



This section comprises small, compact, globose-depressed Helices, 

 of solid, chalky texture, characteristic of western and northwestern 

 Australia. The color is white or whitish, unicolored or having sev- 

 eral spiral bands and lines, of which one just above the periphery 

 is the most prominent and constant. The outer lip is more or less 

 expanded and generally thickened ; the columella is reflexed more 

 or less, often closing the umbilicus. 



Von Martens (in Die Heliceeii) places Rhagada between Dorcasia 

 and Xeropliila ; Pfeiffer (Nomenclator Heliceorum Viventium) be- 

 tween Eremina and Tacliea. It seems to me more naturally grouped 

 under Hadra as a section, the characters of which have a direct re- 

 lation to the conditions of existence in the arid desert region of West 

 Australia. The anatomy is unknown. 



It is somewhat remarkable that two species of the typical form 

 are found in the Malay Archipelago. 



The species falls into two groups : (1) Typical Rhagada, with 

 rounded periphery, species of Western and Northwestern Australia, 

 and (2) Group of H. silveri with the body-whorl keeled, surface 

 strongly obliquely wrinkled, species of South Australia. 



Group of H. reinga Gray (typical forms}. 



H. REINGA Gray. Vol. IV, pi. 36. fig. 39. 



Shell covered-perforate, globose-depressed, rather solid, obliquely 

 striatulate ; whitish ornamented with one chestnut band and several 

 orange-brown lines ; spire subelevated ; whorls 5 J, a little convex, 

 sensibly widening, the last convex beneath, descending in front ; 

 aperture very oblique, narrow, subtriangular-lunar; peristome nar- 

 rowly expanded, labiate with white within, the columellar margin 

 straightened, obtusely and obsoletely unidentate. (Pfr.} 



Alt. 10, greater diam. 15, lesser 13 mill. 



Australia. 



H. Reinga GRAY mss., PFR., Symbolse iii, p. 73 ; Conchyl. Cab., 

 t. 73, f. 8, 9 ; Monographia i, p. 289. REEVE Conch. Icon., f. 772. 

 Rhagada reinga HUTTON Trans. N. Z. Institute xvi, p. 194. 



Formerly supposed to inhabit New Zealand, but now known to be 

 an Australian form. 



H. RICHARDSONII Smith. Vol. IV, pi. 36, figs. 35, 36. 



Shell perforated (perforation concealed), globosely depressed, rather 

 thin, finely striated by the lines of growth, whitish, the last whorl 

 encircled with ten or twelve palish-brown lines (sometimes in worn 



