86 HELIX-DIAGLYPTUS. 



Pitys cryptobidens SUT., Tr. N. Z. Inst. 1890, p. 89, t. 17, f. 7a-c, 

 (shell), M, N (jaw and dentition.) 



Owing to the very poor condition of the radula first examined by 

 Mr. Suter, he considered the teeth zonitoid. This was a mistake, as 

 he subsequently discovered ; the dentition being similiar to Patula. 



Section DIAGLYPTUS Pilsbry. 



Pitys BECK, Index Molluscorurn p. 9, 1837 (name only), type P. 

 oparana B. (undescribed). MCERCH, Catal. Yoldi, p. 6, 1852 (no 

 description ; H. bilamellata Pfr. mentioned.) 



Not Pitys PEASE, P. Z. S. 1871, p. 450. 



Shell elevated-trochiform, umbilicated, the two apical whorls 

 spirally striated the remaining whorls strongly ribbed. Aperture 

 armed with a strong entering parietal lamella and two close col- 

 umellar plicse ; peristome expanded; columella callously thickened 

 within, ending below in a callous nodule. Type Helix bilamellata 

 Pfr. 



This section differs from LAOMA (type H. leimonias) in having 

 the apical whorls spirally striated, the columella strongly calloused 

 within, and the peristome expanded. The anatomy is unknown, 

 but it probably resembles Endodonta rather than Laoma. 



There can be little doubt that Beck's subgenus Pitys was founded 

 for the species cited below ; but as not a line of description of either 

 the subgenus or the species named by Beck was ever given, we can- 

 not accept the name, the identification of which rests wholly upon 

 its etymology. Pease confused Beck's P. oparana with Anton's H. 

 opanica, and accepting the latter as Beck's type, proceeded to define 

 the group ; but since Pitys Pease is demonstrably different from 

 Pitys Beck, we are compelled to reject his revival of the name. I 

 have given a new name to the present group in order to avoid the 

 confusion incident upon the employment of the name Pitys in a 

 sense new to modern conchologists. It cannot be contended that 

 Pitys should be retained for the group, because no description has 

 ever been given except that of Pease. Pitys will therefore be dropped 

 entirely from nomenclature. 



P. BILAMELLATA Pfr. (MANUAL iii, p. 68). Mr. E. A. Smith has 

 changed the name to Patula pagodiformis because bilamellata is 

 preoccupied for a species from St. Helena. See P. Z. S. 1892, p. 262. 

 In case a change is necessary it might have been well to revive the 

 name oparana Beck. 



