MACROCYCLIS. 1 65 



highly modified radula of a tree-snail, but so abnormal that it affords, 

 little ground for conjecture. 



The Indo-Chinese group Ganesella is placed here because it was 

 omitted in its proper place in the Epiphallogonous series, with 

 Chloritis, Planispira, Papuiua, etc. 



Genus MACRO'CYCLIS Beck, 1837. 



Macrocyclis BECK, Index Molluscorum p. 24, for H. peruviana 

 {laxata) and H. cunninghami. ALBERS, Die Hel. p. 128 (restricted 

 to H. laxata). MARTENS, Die Hel. p. 75 (in part). Not Macro- 

 cyclis of American authors, =Selenites. 



Shell disk or quoit shaped with low, convex spire and widely open 

 funnel-shaped umbilicus. Whorls 4?-5, the last large, deeply descend- 

 ing in front ; finely and densely striated; yellowish, not banded. 

 Aperture very oblique, oval, wider than high, the peristome nar- 

 rowly expanded throughout, reflexed below, the ends approaching. 

 Type M. laxata Fer., pi. 22, figs. 11, 12. 



Genitalia, jaw, etc., unknown. Radula strap-shaped as usual, 

 bearing many rows of 33.1.33 teeth, all unicuspid ; centrals with 

 the single conical cusp projecting beyond the basal-plate ; laterals 

 similar but asymmetrical ; marginals like the laterals, but the basal- 

 plates are shorter and the cusps longer, oblique and simple (pi. 51, 

 figs. 1, 2, central with adjacent 3 laterals, 6th and 9th laterals, 12th 

 and 13th transition teeth, 16-18 and 25-33 marginal teeth, of M. 

 laxata}. 



The shell in this group, except in being uniformly light colored, 

 is strikingly like that of the Australian Pedinogyra ; and the denti- 

 tion is altogether similar to Pedinogyra, Panda, Anoglypta and 

 Helicophanta in the total absence of side cusps ; the marginal teeth 

 having long, oblique mesocones as in those Old World genera. In 

 view of the fact that, although unicuspid marginal teeth are pecu- 

 liarly characteristic of the Macroon group, they reappear in a few 

 other Helices, I do not feel justified in associating Macrocyclis with 

 Pedinogyra and its allies. We may better suspend judgment until 

 the genitali.a and jaw give their more definite testimony. The 

 radula is very different from that of Selenites. 



The single species inhabits Chili. 

 M. laxata Fer., iii, 109. Var. banksii Cuming, iii, 109. 



peruviana Lam. maxima Beck. 



deshayesii Anton. umbilicata Anton. 



cincinnus Rve. ? gayi Hupe. 



laxata Rve. 



