INVERTBBEATE PALEONTOLOGY. 383 



operculum in Clathurella and its near allies, &c. There are also peculiarities 

 to be observed in the animals of most of these groups, distinguishing them 

 from the genus under consideration; but, unfortunately, these characters, 

 when not accompanied by corresponding differences in the shell, afford the 

 palaeontologist no direct aid in the classification of fossil species. 



Authorities do not agree in regard to the name that should be retained 

 for this genus. Until comparatively recently, most authors have used 

 Lamarck's name Pleurotoma for it; but, since more attention has been given 

 to the dates of generic names and to the law of priority, the older name 

 Turris has been used to a considerable extent. Even among those who use 

 the latter name, however, there is not entire agreement respecting the author 

 who should be cited as the founder of the genus ; some citing Humphrey, 

 and others Bolten. Undoubtedly, Humphrey used this name a year before 

 Bolten did ; but, as he unfortunately cites no authorities for the species 

 included by him, we cannot be positively sure that any of them belong to 

 this genus. Among others, he mentions T. Babylonia, but he does not refer 

 to Linnaeus, or say that it is Murex Babylonius, Linnaeus. In the same way, 

 he mentions five other species ; but he gives no figures or diagnoses, and, 

 for aught we can learn from his book, they all may have been new species 

 (or supposed by him to be such) of one or more other genera. It is quite 

 probable that his T. Babylonia may have been the Murex Babylonius of Lin- 

 naeus ; yet, under the circumstances, I think we have no right to assume that 

 it was, or that any of his other species belong to this genus. Consequently, 

 I should think that he ought not to be cited as its founder, especially as 

 Bolten distinctly cites, in connection with the name Turris, Murex Babylonius, 

 referring to Martini's figures and description. 



Some reject the name Turris altogether, and retain Lamarck's later 

 name Pleurotoma, on the ground that neither Humphrey nor Bolten gave any 

 generic diagnosis It seems to me, however, that where an author cites a 

 well-known species, referring to figures and description in a published work, 

 or figures and describes the type of his proposed genus himself, where this 

 had not been previously done, he gives more satisfactory means of ascertain- 

 ing the particular genus he had in view than nine-tenths of the diagnoses of 

 the older authors, which often apply equally well to any one of five or six 

 different- genera as now understood; so that even in many of these cases we 

 are altogether guided by the species cited or figured, and not at all by the 

 diagnoses, in identifying such old genera. 



