I-KI'TOTIIYRA. -J4") 



the lower margin fluted; columella arcuate, broad, excavated at 

 position of the umbilicus, and terminating in a tooth-like promi- 

 nence below. Alt. 4o, diaiii. f)f)-(>2 mill. 



\Vc*ti'ni America, Aoapulco to Vnumiirr,- /,/. 



Operculum (pi. 60, figs. (JS ? (; ( s a ) inside deep brown, convex at. up- 

 per, concave toward lower margin ; outside smooth, or rugose at the 

 distal extremity, and white, brownish toward the nucleus. 



Synonyms, Trwlm* t/i/>/>('i-<tn* Zen/midia \<>r;t etc., Chcmnit/, 

 TriH-lin* gibberosus (or Puclujitmnti. gibberosuni) "Cheumitz" of au- 

 thors, (not Trochus in<ic<itilix umbt/irdtn* etc., Chemnitz, T. 

 in&quali* (Jmel. a species of Trochidw), T. diademittus Val, and T. 

 ochraceus Phil. 



The name uieqimlia Martyn, here adopted for this species, has four 

 years priority over Cheninit/'s name. Besides, the latter author 

 was a polynomialist, and merelv copies Murtyn's excellent figures 

 of the species. 



(lenus LEPTOTHYRA (Carpenter) Dull, 1871. 



Shell small or minute, globose-depressed, solid, compact; umbili- 

 cate or imperforate, whorls .'>-7, spirally sculptured, the last generally 

 somewhat dcfiexed at the aperture; aperture subcircular, white and 

 nacreous within; columella generally but not always bluntly den- 

 ticulate near the base. Operculum subcircular, nearly Hut or 

 concavo-convex, inside with a very thin corneous layer, slightly 

 convex, with many gradually increasing whorls, the nucleus sub- 

 central; outside calcareous, subspiral, with a slightly convex con- 

 centric elevation or ridge around the margin, most prominent at 

 its termination, the middle portion concave and more or less rugose. 



The species are numerous, inhabiting nearly all tropical and sub- 

 tropical seas; but most numerous in the Pacific. 



The synonymy includes Collonia Gray (in part), Col Ionia of most 

 authors, Leptony.v and Homalopomo Carpenter (preoc.), Cantrainea 

 Jeffreys, Cantraiueia Fischer, Anadema H. & A. Adams. The 

 genus is very homogeneous, and neither of the subgenera proposed, 

 (Cantrainea Jeff, for L. carinata, and An<nl('imt, Ads. for L. coelata 

 Ad. have sufficient characters for any systematic rank. 



The characters of the dentition are discussed on p. 188. The 

 rank and position of this group has been the subject of considerable 

 controversy; but partly, perhaps, on account of the minute size of 

 the species, partly because of the scattered and inexact condition of 



