THYSANOPHORA. 57 



The forms of this genus are so little known anatomically that any 

 attempt at sectional division would now be premature. By purely 

 conchological standards, three sections are indicated : (a) Thysano- 

 pJwra restricted, including small forms having cuticular riblets 

 more oblique than, and crossing, the growth-lines. This may include- 

 Ptychopatula (type c.ceea, pi. 16, fig. 4) which differs in being globosely 

 elevated with only a minute umbilicus. Acanthinula of Strebeland 

 v. Martens (in Biol. Centr. Amer.) is a synonym. (2) forms of the 

 type of vortex, with smoother surface, the spire varying from flat to 

 pyramidal ; mostly Antillean. . T. ptychodes, T. turbiniformis (pi. 

 16, figs. 1, 2), etc., belong here also. (3) Larger forms, with the 

 spire mostly depressed, sometimes concave, the surface minutely 

 roughened or bristly, such as T. stigmatica (pi. 16, figs. 8, 9, 10), T 

 suavis, T. velutina, etc., from the Greater Antilles, and T. sigmoides 

 from Guatemala. 



Species of the mainland, Trinidad to Texas and Florida, etc. 



T. conspurcatella Morel, iii. 50. T. venezuelensis Jouss. viii, 112. 



T. impura Pfr. iii, 50. T. rojasi Jouss. viii, 112. 



T. incrustata Poey. ii, 204. T. vortex Pir. iii, 93. 



T. ingersolli Bid. iii, 101. T. turbinella Morel, iii, 51. 



T. paleosa Streb. iii, 50. T. csecoides Gupp. iii, 55. 



T. granum Streb. iii, 55. T. guatemalensis C. & F. ii, 174. 



T. ierensis Gupp. iii. 55. T. coloba Pils. 



T. plagioptycha Sh. ii, 174. T. punctum Morel, iii, 53. 



T. dioscoricola C. B. Ad. ii, 174. T. intonsa Pils. viii, 111. 



T. cseca Guppy. iii, 55. T. sigmoides Morel, iii, 101. 



T. bactricola Guppy. iii, 55. vitrinoides Tristr. 



T. hornii Gabb. iii, 21. 



[Of the above species, T. granum and ierensis are probably mere 

 varieties of plagioptycha, and T. cceca and punctum varieties of dios- 

 coricola. Specimens of all the above, except turbinella, guatemalensis, 

 venezuelensis, rojasi and punctum are in the collection of the 

 Academy.] 



Species of the West Indies and Bermuda,. 



T. alveus C. B. Ad. iii, 98. T. musicola Shutt. iii, 97. 



T. angustispira C. B. Ad. iii, 97. v. major Crosse. 



T. anthoniana C. B. Ad. iii, 96. T. peraffinis C. B. Ad. iii, 98. 



