8 ANNALS NEW YORK ACADEMY OF SCIENCES 



the name of a genus of hydroids, and the confusion that would arise in 

 the literature furnishes another reason for avoiding such a change. 



In the first published description of the genus Cerithium by Bruguiere 

 no genotype was designated, and the first to make a definite selection was 

 Lamarck [1799].* He chose Murex aluco Linne, which was described 

 by Bruguiere with the name of Cerite chenille. This shell belongs to 

 the first of the three groups described by Bruguiere, and it might well 

 remain the type of that group to which the name Pseudovertagus has 

 since been applied. It does not belong in the same group with the shell 

 to which Columns gave the name of Cerithium, as will be seen by com- 

 paring the life histories of the two species as given on plate iii;, figs. 2, 

 3, 4 ; plate iv, figs. 2, 3 ; plate v, figs. 1, 2 ; plate iii, fig. 6 ; plate iv. figs. 

 6, 7 ; plate v, figs. 5, 6, and plate vi, figs. 4, 5. Lamarck himself seems 

 to have been dissatisfied with his own choice of a genotype, for two years 

 later [1801, p. 85] he redescribed the genus and mentioned Cerithium 

 nodulosum as an example of it. 



Later authors have adjusted the claims of their predecessors in various 

 v/ays. Most credit the genus to Bruguiere, but others refer it to La- 

 marck or Adanson. A few of these may be mentioned: thus Montfort 

 [1810] credits the genus to Lamarck, choosing the genotype selected by 

 him in 1799. Link [1807] and Schumacher [1817] solve the difficulty 

 by dividing the genus into two groups, the former following Lamarck, in 

 1799, for his first group, and Bruguiere, with Cerithium adansoni as an 

 example of his second group, to which he gives the name Aluco. Schu- 

 macher retains the name Cerithium for both his groups, crediting them 

 to Lamarck, with C. aluco as genotype for one and C. nodulosum for the 

 other. Among the authors who refer the genus to Adanson are Deshayes 

 [1824], d'Orbigny [1842-1843], Sowerby [1855], Fischer [1887] and 

 Tryon [1887]. Bruguiere, being the first to describe tlie genus as such, 

 is still more widely recognized, and a few of the authors who have fol- 

 lowed him are Swainson [1840], Eeeve [1866], Cossmann [1906] and 

 Dall [1907]. 



In the choice of a genotype equal diversity is shown, for Fischer, while 

 he refers the genus to Adanson, chooses C. nodulosum as the genotype. 

 Deshayes is consistent in choosing for the type of the genus C. adansoni. 

 Of those M'lio refer the genus to Bruguiere, Swainson and Cossmann 

 choose C. nodulosuiu . and Dall and Dautzenberg and Dollfus [1882- 

 1885] choose ^furex aJuco Ltnxk as the type of the genus. 



Summarizing the facts already given, it appears that Columnas was 



* The author has been unable to see this work, and is indebted to DaU [1907, p. 364] 

 for the reference. 



