230 HELIX-OBBA. 



Carocolla parmula BROD. P. Z. S. 1841, p. 38. REEVE, Conch. 

 Syst. ii, t. 167, f. 7. Helix parmula PFR. Monographia i, p. 394 ; 

 Conchyl. Cab., p. 210, t. 106, f. 4-6. REEVE, Conch. Icon. f. 120. 

 DESH. in Fer., Hist., p. 356, t. 101, f. 19-21. HIDALGO, Journ. 

 de Conchyl. 1887, p. 100. v. MOLL., Bericht Senckenb. naturfor- 

 sch. Ges. 1890, p. 217. ? H. discus DESH. (not Thorn.) in Fer., 

 Hist., p. 360, t. 62 A, f. 4. 



More flattened than any other species; very acutely keeled, with 

 a somewhat lanceolate horizontal mouth. The bands are nearly 

 obsolete. 



A small form is figured on pi. 65, figs. 76, 77. It measures, alt. 10, 

 diam. 27 2, mill. It is from Zebu, and was obtained direct from the 

 collector. 



Var. DISCUS Desh. (PI. 57, figs. 91, 92, 93.) Thin, white 

 (bleached?), striate; whorls 5? ; umbilicus wider than in H. par- 

 mula. 



This form, described by Deshayes from a single specimen of un- 

 known origin, and not found by recent collectors, is probably to be 

 referred to H. parmula as a variety or individual variation. 



Form OBSCURA Mollendorff. Shell smaller, plicate-striate, cor- 

 neous-brown, bands obscure brown. Alt. 9?, diam. 28 mill. 



Matutinao, Zebu. 



Form ELEVATA Moll. Shell smaller, more solid, strongly rugose- 

 striate ; spire more elevated. Alt. 14, diam, 32? mill. ; alt. 13, 

 diam. 27 mill. 



A still more elevated form, trochoidea Moll., measures, alt 13, 

 diam. 22f-26? mill. It is from Sambuan and Malabuyoc, Zebu. 



The elevated forms tend to assume a scalariform aspect. See von 

 Mollendorff, I. c. 



H. BUSTOI Hidalgo. PL 60, figs. , 13, 14. 



Shell moderately umbilicated, very much depressed, discoidal, 

 carinated, thin, subpelluced, sculptured above with obsolete oblique 

 costulse, striatulate beneath. Whitish, two-zoned with yellowish- 

 brown. Spire little raised ; apex flat, smooth. Whorls 4J, a little 

 convex, the last but little wider than the next inner one, angularly 

 deflexed in front ; base convex ; carina very acute, white, marked 

 by an impressed line. Umbilicus one-seventh the diameter. Aper- 

 ture horizontal, sublanceolate ; peristome simple, margins joined by 



