TRITON. 7 



smooth or nodulous ; the canal long or short ; the outer lip 

 erenated or denticulated within. 



Opercnlum ovate, its growth annular either from a sub-apical 

 or submarginal nucleus. 



Whilst the lingual armature of Triton allies it elosety with 

 Dolium, etc., among the so-called tsenioglossate mollusks, the 

 affinities of the animal are on the whole closer, and those of the 

 shell decided^ so, to Muricidae.* It may be considered a 

 connecting link between the two groups, but certainly cannot be 

 safely removed from the vicinity of the latter, to which it is not 

 only allied by its operculum (which is entirely different from that 

 of Dolium), but so closely by the shell in some instances, that 

 the assignment of the generic position is quite arbitrary. 



The Tritons are distinctly tropical in distribution, no species 

 inhabiting the colder seas. The species are numerous and beau- 

 tiful, presenting a great range of variation in size and color ; one 

 species being almost the largest of gasteropod mollusks, attaining 

 a length of one and a half feet, whilst others, belonging to the 

 Epidromoid section, do not exceed a half inch in length. The' 

 cancellated forms are chiefly East Indian, and are dredged in sand 

 in deep water ; the West Coast of America group, covered with 

 a rough epidermis, is obtained in sandy mud at from six to thirt}^ 

 fathoms' depth. A number of species have a world-wide distri- 

 bution , which is doubtless due to their free-swimming or pelagic 

 larvae. These, unlike the Mu rices, but like the Purpuraj,f are 

 very different at first from the adult both in animal and shell, 

 undergoing a metamorphosis at a period subsequent to hatching. 



I adopt the well-known name Triton in preference to the pre- 

 viously given Tritoniiim of Olivier, believing that the interests 

 of science are best conserved by keeping the nomenclature as 

 stable as possible. Triton has been used in other departments 

 of zoology-, but so have many other generic names, which are 

 nevertheless accepted without question. The fact is, that prac- 

 tical common sense has quietly shelved the British Association 

 rule forbidding the use of a generic name in more than one 

 branch of zoology. In these days only the very few enjoying 



* See Vol. 2, Manual of Conchology, page 67. 

 f Vol. II, plate 8. 



