24 HELIX HEMITROCHUS. 



raphia v, p. 239. H. phcedra PFR. P. Z. S. 1852, p. 138 ; Conchyl. 

 Cab. p. 477, t. 158, f. 16-18 ; Monogr. iii, p. 148. REEVE, Conch. 

 Icon. f. 768. 



I can see no difference between H. phsedra and H. justi of Pfeiffer. 

 The figures 56-58 on pi. 12 represent the latter form. 



Section III. HEMITROCHUS Swainson, 1840. 



Hemitrochus SWAINS. Shells and Shell-fish, p. 331. BINNEY 

 and BLAND, Ann. Lye. N. H. of N. Y. x, p. 342, 1873. BINNEY 

 Proc. Phila. Acad. 1874, p. 56; Terr. Moll. U. S. v, p. 174, 1878; 

 Ann. N. Y. Acad. Sei. iii, p. 90 PFR. Mai. Blatt, 1877, p. 8. 

 Polytcenia ALBERS-MARTENS Die Heliceen, 1860, p. 129. Polymita 

 (in part) ALBERS and other authors Phcedra (in part) ALBERS, 

 Die Heliceen, 1850, p. 100. 



A group of brightly painted species, mostly confined to the 

 Bahamas. They are generally more globose and more opaque than 

 the species of Cysticopsis or Plagioptycha. 



The name of this section being older than Plagioptycha, Dialeuca, 

 Coryda, etc., I have used in a wider sense to designate the group 

 including all of these sections. 



Most of the named forms of Hemitrochus of the Bahamas are 

 only incipient species, not differentiated enough to have really tangi- 

 ble specific characters. I have examined very extensive suites, and 

 finding the greatest difficulty in so defining the various forms 

 that they may be separated into species, finally decided to point out 

 the differences (where there are any) between the several species, 

 varieties, races, or whatever the reader chooses to call the muta- 

 tions, and leave the question of their rank open until we know posi- 

 tively to what extent actual coalescence occurs between the forms. 

 I have made my descriptions comparative, as far as seemed desira- 

 ble ; and since H. varians, of the Florida Keys and New Provi- 

 dence is a species well-known to all conchologists, I have used it as 

 a basis for comparison. 



H. VARIANS Menke. PI. 13, figs. 59-63. 



Imperforate, except for a narrow chink behind the columellar 

 lip, conical, solid, opaque, white or rose-tinted, unicolored or marked 

 with spiral bands of brown, or suffused all over and streaked with 

 chestnut, with or without spiral bands of white or dark ; apex pink, 

 purplish or white ; surface marked slightly by growth-lines ; spire 



