294 HELIX-PLANISPIRA. 



Group of H. tortilabia. 



A swollen crest developed behind the upper and outer margins of 

 the lip. Species of New Guinea. 



H. TORTILABIA Lesson. PI. 36, figs. 30, 31, 32 ; pi. 60, figs. 7, 8, 9. 



Shell umbilicated, suborbicular, discoidal, yellowish-white, uni- 

 colored or bifasciate with reddish brown ; spire plane ; whorls 5, a 

 little convex, the last subdepressed, a little deflexed in front and hav- 

 ing a gibbous ridge or crest above, constricted beneath ; umbilicus 

 moderate. Aperture very oblique, rounded-lunar ; peristome re- 

 flexed, margins converging. 



Alt. 9*, greater diam. 22, lesser 19 mill. (P/r.) 



Western New Guinea ; Sorong and Aru islands. 



H. tortilabia LESSON, Voy. de la Coquille, Zool. II, p. 311, t. 13, 

 f. 1. PHIL. Abbild. i, p. 152, Helix t. 5, f. 4. PFR. Conchy 1. Cab., 

 p. 129, t. 90, f. 10-12; Mon. Hel. Viv. i, p. 388. EVE, Conch. 

 Icon., f. 498. MARTENS, Ostas. Zool. ii, p. 391. H. (Cristigibba) 

 tortilabia Less. TAPP. CAN. Ann. Mus. Civ. Genov. xix, p. 171, 1883. 

 H. (Planispira) tortilabia Less., PFR. Versuch. etc., p. 136 ; 

 Nomencl. Hel. Viv., p. 182. TAPP. CAN. Ann. Mus. Civ. Genov. 

 vi, p. 561, 1874 ; ix, p. 289, 1876-77 ; Bull. Soc. Zool. France, 1878, 

 p. 270. H. gibbosula HOMBRON & JACQUINOT, Voy. au Pole Sud, 

 atlas, t. 5, f. 14-16 ; and ROUSSEAU in text of same, p. 14. H. torti- 

 collis TAPP. CAN. Ann. Mus. Civ. Genov. vi, 1874, p. 561, 562 (and 

 of Le Guillou ?) 



Two principal forms of this species are recognized by Tapparone 

 Canefri. 



FORM A. Shell relatively larger ; aperture somewhat oval, am- 

 ple ; superior margin of the peristome wider and less expanded out- 

 wardly. The following color-forms occur : 



Typical. Shell white all over with two brown bands. This is the 

 typical form figured by Lesson. 



a. White all over, without bands, covered with a very thin, yel- 

 lowish epidermis. This is H. gibbosula H. & J. and tortilabia Phil. 

 See figs. 30-32 of pi. 36. 



b. Shell bandless, white, the first whorl of the spire, the peristome 

 and the palatal region within and outside, bright rose colored. One 

 example from Aru Island. 



