280 AULACOSPIRA, ACANTHI.NULA. 



Anatomy unknown. The species live in clefts and crevices of 

 limestone rocks, in which the flatness of their shells allows them 

 ready access, and like Vallonia they seem to be gregarious. The 

 species now known are fromCebu, Busuanga, Luzon and the Island 

 Ilin, near Mindoro ; but it probably will prove to have many more 

 species in other islands of the Philippine group. 



In deference to the opinion of Mollendorff I give the group place 

 herein the vicinity of Fruticicola; but my own course would be to 

 place it next to Eulota or even as a subgenus within that genus. 

 Compare the similar group Platypetasus (p. 207). I am now disposed 

 to consider Pupisoma (see p. 52), as well as Aulacospira, as branches 

 of the Eulota stock, parallel to, rather than allied to Acanthinula 

 and Vallonia which seem to be early branches of the Hygromia 

 phylum. They will probably be found to have the genitalia con- 

 siderably simplified by suppression of accessory organs, and the 

 marginal teeth multicuspid ; these changes usually accompanying 

 such great reduction in the size of snails. 



Mollendorff establishes two sections: 



Aulacospira s. str. (of which Micropetasus is an absolute synonym). 

 Keel extending to aperture ; perietome continuous and free. 



Pseudostreptaxis Mlldff. (1. c. p. 225). Penultimate whorl dis- 

 tinctly deviating ; the last whorl not keeled, cylindrical ; aperture 

 5-toothed, the peristome not continuous. One species A. azpeitice. 



A. hololoma Mlldff., viii, 198. A. porrecta Quadr. & Mlldff., 

 A. mucronata Mlldff, viii, 198. Nachrbl. 1894, p. 95. 

 A. scalatella Mlldff, viii, 199. A. azpeithse Hid., viii, 199. 



Genus ACANTHINULA Beck, 1846. 



Acanthinula BECK, Amtl. Ber. Vers. Kiel, 1846, p. 122. v. MART. 

 in Die Hel., 1860, p. WO.Euacanthinula WEST., Fauna, p. 16. 



Shell minute, pyramidal or globosely-turbinate, thin, brown, 

 minutely umbilicated. Epidermis raised into lamellae crossing the 

 whorls. Aperture subvertical, semilunar or subcircular, the lip 

 acute, expanded toward columellar insertion, the margins remote. 

 Type A. aculeata Mull., pi. 70, figs. 26, 27, 28. 



Animal apparently with even, not crenulated foot-margins ; ovi- 

 parous? Jaw arched, with numerous flat ribs. Genitalia (pi. 63, 



