SERTULARIA. 135 



The multitude of zoophytes having greatly increased, especially of 

 later years, with the number of observers, has demanded its partition into 

 lesser sections for convenience. But I am not aware that as yet the ad- 

 vances of knowledge actually admits the various divisions and subdivisions 

 proposed by modern naturalists. I fear we are premature in receiving 

 some of them ; for, allowing both their zeal and their intelligence, as ob- 

 servers, it seems to me, — I speak it with deference, — that we are still too 

 deficient in facts and in Jigtires, those radical elements, whereon alone un- 

 erring systems can be founded. 



A strong propensity for the alteration of established nomenclature, 

 attended by an undue anxiety for the constitution of additional genera, has 

 recently predominated. Hence, precipitate observation has assumed tri- 

 vial distinctions as important characters, to support the addition or the 

 change, instead of permitting the favoured subject to merge among its 

 fellow species of some well-known and well-marked genus. 



Probably the multiplication of genera will prove less expedient than 

 the enrolment of species. It can be scarcely doubted that, with the pro- 

 gress of more profound learning and investigation, so many analogies will 

 be found as to consolidate a number of species into a separate genus, or 

 to unite them to one already established : Also, that by the same means, 

 certain genera now admitted would be reduced to species. The constitution 

 of genera should repose on strong and indelible features, easily recognised. 

 It should be framed on species bearing some prominent reciprocal qua- 

 lities of form or of habits. But to found on the shape, the number and 

 position of the hairs, bristles, pencils, scales, warts, and the like, newly re- 

 vealed by every higher microscopical power, especially in the observation 

 of minuter animals, would almost require, for the reception of each, some 

 additional genus. 



Perhaps as many animals, particidarly of the smaller tribes, remain 

 for discovery as those already known. 



But I have never seen two animals exactly alike, however slight the 

 difference. On very minute comparison of two species, unless the ob- 

 server's views be proportionally enlarged, he will often question whether 

 each does not pertain to another genus. 



