TRITONID^. 12o 



Syn. — Bufo, Montf, Bnfonaria, Schum. Gyrinium, Link. 

 Apollon, Montf. Bursa, Bolten. Semiranella, Gregorio. 



Distr. — 36 sp. Tropical seas, world-wide. Fossil, 23 sp. 

 Eocene. R. albivaricosa, Reeve (xlvi, 65). H. spinosa^ Lam. 

 (xlvi, 66). 



Shell ovate or oblong, compressed, with two rows of continuous 

 varices, one on each side ; aperture oval ; columella arcuated and 

 ridged, or crenulated ; canal short, recurved ; outer lip crenated. 



The tentacles are commonly somewhat closer together than in 

 Triton, and the head is longer and narrower than in Murex and 

 Fusus ; the eyes in some species are nearly basal, but are gener- 

 ally placed about the middle of the tentacles on their outer 

 sides ; the siphon is short and directed upwards ; the foot larger 

 than in Triton, Murex, or Fusus, and considerably dilated both 

 before and behind ; the mantle does not appear to be furnished 

 with fimbriated processes as seen in some Murices. In some 

 species the trunk is enormously developed, whilst in others it is 

 not protruded, in the usual condition of the animal. Operculum 

 ovate, horny, with a lateral nucleus and semicircular elements. 



The species are inhabitants of warm seas, and principally 

 tropical : those of the typical group having winged varices live 

 in deep water, whilst the nodose species forming the subgenus 

 Lampas, are found at less depth, and prefer coral reefs and 

 rocks. The animal is active in its movements. Bupleura, for- 

 merly considered a subgeneric grovip of Ranella, is now classed 

 with Muricinse, partly on account of the lingual dentition of one 

 of its species. 



1 have retained the generic name Ranella, in preference to 

 Bursa, Gyrinium, Bufo, Rana, etc., all of which have priority, 

 but were obscurely published and have never attained general 

 acceptance. 



Mr. Macdonald thus describes the larval state of Ranella : 



" I next observed a stout little shell, much resembling a Mac- 

 gillivrayia in form, but having the spire more minute and sharply 

 marked, and the whorls beset with epidermic spines, disposed 

 in close spiral lines. The microscopic examination of the animal 

 gave unmistakable proof of its being a Ranella, the lingual 

 dentition agreeing, at least generically, with my figures and 

 specimens. On examining the operculum, which in Ranella is 

 so very remarkable, exhibiting three successive stages of growth, 

 1 found that it was quite of the same character, only that it had 

 but yet attained the second stage. Finally, on comparing the 

 whole operculum, and the little shell respectively, with the 

 nucleus of the operculum and the apex of the shell of an adult 

 Ranella, 1 could detect no points of difference, even with mag- 

 nifying powers; the conclusion, therefore, is irresistible, that 



