94 THE NAUTILUS. 



typical Thysanophoras as T. crnispurcatella and hornii. There 

 are also species intermediate in shape, such as T. fuscula and 

 T. intonsa, leading from the depressed to the conic forms. It- 

 would be easy to tell absolutely where these snails belong if 

 specimens containing the animal were available. 



Though not strictly germane to the subject of this paper, it 

 may be mentioned that Trichodiscina crinita Fulton, Proc. 

 Malac. Soc., London, XII, 240, from Colombia, is a species of 

 Ihysanophora. Some allied forms are known from Venezuela 

 as well as from Mexico. It has about the shape of T. conspurca- 

 tella or hornii. The latter, when perfectly preserved, also has 

 hairs. 



THYSANOPHORA FUSCULA (C. B. Adams). Fig. 1. 



Helix fuscula C. B. Ad., Contrib. to Conch, no. 2, 1849, p. 35. 



Ihysanophora fischeri Pilsbry, Proc. A. N. S. Phil a. 1903, p. 

 763, pi. 49, fig. 6, 6a. 



This Jamaican species has a wider umbilicus than others of 

 the group, contained about 6.4 times in the diameter of shell. 

 The figures are from a specimen from Adams, measuring: Alt. 

 2.15, diani. 2.55 mm., umbilicus 0.4 mm. 



The sculpture of rather coarse growth wrinkles and minute, 

 oblique, retractive cuticular threads, does not differ materially 

 from that of T. plagioptycha. 



I can see no material difference between the Jamaican shells 

 and those taken near Victoria, Tamaulipas by S. N. Rhoads, 

 and in the region of Tampico by A. A. Hinkley, and which I 

 described as T. fischeri. In these the umbilicus is contained 

 about 7 times in the diameter. When describing this form I 

 did not think to compare with the Jamaican snail. Like some 

 other minute species of the region, it will probably be found to 

 be more widely spread than now known. 



THYSANOPHORA PLAGIOPTYCHA (Shuttleworth). Fig. 2. 



Helix plagioptycha Shuttl., Mittheil. der Naturforschenden 

 Gesellschaft in Bern, 1854, p. 37 (Porto Rico and Vieque). 



Helix ierensis Guppy, Proc. Scient. Asso. Trinidad. 1869, p. 

 242; Amer. Journ. of Conch. VI, 1871, p. 307, pi. 17, fig. 4. 

 Pfeiffer, Mon. Hel. Viv. VII, p. 549. 



