52 JOURNAL OF CONCHOLOGY, VOI.. II, NO. 2, APRIL, 1904. 



a number of species under the name ampullacea, and the trivial name 

 "cordon bleu," which he used with it was applied to an American 

 species by Favanne. In 1801, in his "Systeme des animaux sans 

 vertebres" (p. 93), Lamarck adds to his diagnosis the statement 

 "muni d'un opercule cornd" This must be taken as settling the 

 name of AmpuUaria definitely on the species with a horny operculum, 

 leaving those with a calcareous operculum to carry the Boltenian 

 designation, Pila. Gray (1824) and Guilding (1828) afterwards 

 divided the genus in the same sense. Gray's Marisa being intended 

 to cover Atnpitllaria s.s., and not the Helix cortiic-arietis which has 

 so persistently and inaccurately been asserted to be the type of Marisa. 

 It is a somewhat singular fact that the Old World forms appear to be 

 dextral with an externally calcareous operculum, or sinistral with a 

 horny one; while those of America all have an operculum externally 

 horny, and are dextral. Of the latter South America is the great 

 metropolis, most of the species being found in the Caribbeean or 

 Atlantic drainage. In the highlands of Colombia, Ecuador and Peru, 

 a small group of species is found in which the pillar is heavy and 

 callous, the umbilicus closed with a pad of callus, as in Natica clausa, 

 while the other characters are as usual in Ainpullaria. AmpuUaria 

 columellaris Gould may serve as type of this section which I 

 propose to call Liiimopomus} The sinistral forms with a horny 

 operculum are wholly African. The forms with a calcareous oper- 

 culum and dextral, globose shell, are African or Asiatic. The eggs 

 have a calcareous coat and are laid in large masses on the stems of 

 reeds above water. They are usually, when fresh, of very attractive 

 colors — crimson, pale pink, or bluish green — which are apt to fade 

 when the egg-mass is dried or put in alcohol. The nepionic shell 

 has spiral rows of delicate hairs and a well developed operculum 

 before it leaves the egg-shell, the Oriental species even have the shelly 

 coat of the operculum developed before hatching. 



The following key will enable one to trace the subdivisions of the 

 group:— 



Operculum externally calcareous. Pila. 



Respiratory siphon long. Shell solid. Color uniform 



or spirally banded. Pila s.s. 



Shell very delicate. Color nebulous. Saitlea. 



Operculum externally horny. AmpuUaria. 



Shell dextral. 



Respiratory siphon long. 



Pillar not callous, umbilicus open. 



Shell globose. AmpuUaria s.s. 



I A. castilloi Sowerby, appears also to belong to this group. 



