114 MADEIRAN SPECIES OF LAUBIA. 



tooth, aud with the latter defining the sinvdus. Basal tooth 

 small, sometimes divided, and like the palatals, arising from 

 a callous ridge. Peristome somewhat expanded ; parietal 

 callus thin. 



Length 3.6, diam. 2.1 mm. ; 6% whorls. 



Length 3.5, diam. 1.9 mm. ; 6% whorls. 



Length 2.7, diam. 1.6 mm.; (Pleistocene). 



Madeira group, Porto Santo : summits of Pico de Facho 

 (fig. 2), Pico Branco, etc.. in crevices and on ledges of the 

 rocks among vegetable detritus; Pleistocene of Zimbral 

 d 'Areia ( Wollaston ) . 



Helix C. colathiscus Lowe, Cambr. Philos. Soc. iv, 1831, 

 p. 64, pi. 6, f. 34. — Pupa calathiscios Lowe, P. Zool. Soc. 

 1854, p. 212. — Pfr., Monogr. ii, 1845. p. 244. — Woleaston, 

 Test. Atl. p. 234. 



L. calathiscus is larger than any of the related ribbed 

 species, further distinguished by the small parietal lamella, 

 peculiar upper-palatal fold and the strong sculpture. It is 

 type of the section Eryma, Albers. 



This species is found only at high elevations. The fossil 

 form, of which specimens collected by Professor Cockerell 

 are before me, is smaller than recent examples, a peculiarity 

 already noticed by Wollaston. 



Section Wollaston ula Pils. 



Wollastonvla Pilsbry. this volume pp. 45, 69 (Aug. 29, 

 1922). 



Leiostyliform Lauria 1 in which the parietal lamella emerges, 

 and projects into the aperture further than the angular; 

 upper-palatal fold very long, much exceeding the lower, both 

 immersed; sinulus nearly closed. The shell is small and 

 ribbed in the single species known. 



L. gibba, the type of this section, is perhaps the most 

 specialized of Madeiran Laurias ; indeed its evident approach 

 to extinction maj^ be due to over-specialization of the teeth. 



