56 



rUOCKEDINGS OF TUK MALACOhOGICAL SOCIETY. 



Type in the British Museum. 



Tiiis new species is based on a specimen found with C. anserina in 

 the Theobaki Collection of the Eritish Museum, It differs from that 

 species in having a more conical spire and a wider umbilicus, the base 

 is less inflated, and conse(iuently the aperture is more dilated laterally. 

 It is also differently coiled, for, while measuring one-fifth less in 

 diaTueter, it possesses halt a whorl more, and the hair-scars, moreover, 

 are much finer and more crowded, while the presence of a supra- 

 ]ieripheral band unfortunately omitted in the above figure still 

 further differentiates it from C. anserma. 



C. theohaldi bears a striking resemblance to C. ffanciscanortcm, 

 (iredler, a Ciiinese shell, but it has the umbilicus a little more con- 

 tracted, the spire is relatively higher, and the aperture is less dilated 

 laterally, while the coluniellar margin ascends less obliquely; the 

 hair-scars are also finer. 



I have much pleasure in associating the late Mr. W. Theobald's 

 name with this new species. 



Plectotkopis nutans, n.sp. 



Shell depressed-conoid, rather widely and perspectively umbilicated, 

 thin, light corneous under a pale-yellowish corneous deciduous cuticle, 

 finely and somewhat irregularly striated, very minutely spirally 

 striated above, the base covered with much coarser incised, slightly 

 wavy spirals. Spire low, suture linear, apex acute. Whorls 5^-5 J, 

 increasing slowly and regularly at first, tlie last rather suddenly ; 

 flattened above, the last conve.K below, keeled at the periphery, the 



keel being rather pinched above and below, angulated around the 

 umbilicus, not dilated at the mouth, very shortly and slightly de- 

 scending in front. Aperture oblique, siib-hastate, margins approaching, 

 united by a very thin callus on the parietal wall; peristome rather 

 thin, scarcely thickened, but distinctly expanded, slightly reflexed ; 

 upper margin slightly curved, forming an ohtuse angle with the outer 

 margin, which is also slightlv curved, the basal margin strongly 



