90 HELIX-THERSITES. 



Section I. THERSITES Pfeiffer, 1856. 



Thersites PFR. Malak. Blatter ii, 1856, p. 141 ; Nomencl. Hel. 

 Viv., p. 178, 1881. First species H. Riclimondiana. ALBERS, Die 

 Heliceen (edit. Martens) p. 157, 1861 (restricted to H. Riclunon- 

 dianct). Merope (in part) of ALBERS and many other authors. 



Shell perforate when young, closed in the adult, trochoidal or 

 lens-shaped, acutely keeled, moderately solid, dark chestnut-brown, 

 or light with dark bands at suture, periphery and umbilicus. Sur- 

 face covered (at least on the base) with a minute, dense sculpture of 

 fine wrinkles, generally zigzagged or irregular, often cut into gran- 

 ules in places. Whorls 5 to 6, flat or nearly so, the last whorl on 

 its latter half pinched or furrowed above and below the keel, or 

 with a visible tendency to be flattened or modified there ; deflexed 

 in front. Aperture triangular, very oblique, angular, the outer lip 

 expanded, sinuous above, columellar lip reflexed, adnate. 



This section, like Pedinogyra, is restricted to eastern Australia. 

 Its more prominent shell-characters are the narrowly perforated axis 

 closed in the adult, the trochoidal acutelv keeled form, the flattened 



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or furrowed surface of the last whorl in the region of the periphery, 

 and especially the finely, irregularly wrinkled surface-sculpture. Any 

 one who will carefully compare the two species I have grouped in 

 Thersites and examine them under a lens, will, I doubt not, agree 

 with me in associating H. novcehollandice with H. richmondiana, 

 and in dismembering the section Merope of Albers, as that section is 

 constituted in Die Heliceen, and in Pfeiffer's Nomenclator Helice- 

 orum Viventium, restricting it to H. fringilla, the type species. 



Since the above paragraph was written I have noticed with pleas- 

 ure that Dr. Dohrn has already separated H. novcehollandice from 

 fringilla, and placed the former in Thersites. 



H. RICHMONDIANA Pfeiffer. PI. 20, figs. 34, 35, 36. 



Shell large, trochiform, flat below, acutely carinated at the periph- 

 ery, imperforate. 



It is solid, strong, opaque, dark brown all over ; the surface rather 

 smooth, growth-striae light ; under a lens there may be seen a very 

 peculiar pattern of fine zigzag wrinkles on the base and just above 

 the keel. The spire is conical, terminating in an obtuse rounded 

 apex. Suture linear. Whorls 6, flat, the last compressed into an 

 acute projecting flange or keel at the periphery ; the latter half of 

 the whorl distorted by a deeply impressed furrow above and one be- 



