198 DR. J. E. GRAY ON THE CETACEANS. [May, 26, 



If the arrangement of the species into genera requires mature deli- 

 heration and the study of the value of the different characters ob- 

 served as to their permanence and variability in each group (and the 

 variations in different organs are often of very different value in this 

 respect in very nearly allied groups), then the arrangement of the 

 minor groups into larger and larger ones, according to my experi- 

 ence, and indeed as any one may a priori suppose, demands a greater . 

 power of comparison and reasoning, since there are a greater number 

 of facts, of characters, and of resemblances or differences, and of varia- 

 tion or permanence, to be considered and reasoned on — that is to say, if 

 the constituents of the larger groups are conscientiously examined 

 and determined on, as they must be to render them of value for the 

 purposes above stated. 



I am aware that this is not the feeling of many zoologists, but I 

 believe this arises from most zoologists restraining themselves to the 

 study of a limited number of species or genera. This is proved by 

 the fact that many zoologists pay great attention as to who was the 

 first person who gave the name to a genus, though the genus may 

 have been restricted, or even extended, and its characters completely 

 altered since the name was first applied, but pay little or no atten- 

 tion to the first person who formed a group, or to the synonymy or 

 history of the changes which have taken place in the characters or 

 arrangement of the group or genera themselves. This is not the 

 case with botanists, who are generally much better grounded in the 

 philosophy of science. They are careful in giving the synonyms 

 of the families and subfamilies, as may be seen in works of DeCan- 

 doUe and others. And it is very desirable that the same attention 

 should be paid to the subject in zoological essays. 



The order Cetacea must be divided into two suborders, viz. Cete 

 and SiRENiA. I have nothing to add to the arrangement of the 

 second suborder. 



Suborder I. Cete. 



Skin smooth, bald. Teats two, inguinal. Limbs clawless ; the 

 fore limbs fin-shaped ; hinder united, forming a forked horizontal 

 tail. Nostrils enlarged into blowers. Carnivorous. 



I. The 7iostrils longitudinal, parallel or diverging, covered with a 

 valve, one often larger and more developed. 



Fam. 1. BaljEnidjE. 



Head very large, depressed. Nostrils separate, nuchal. Teeth 

 not developed in the adult. Palate furnished with transverse horny 

 fringed plates of baleen or whalebone. 



a. Dorsal Jin none ; belly smooth ; baleen elongate, slender ; vertebrcB 

 of neck united; pectoral broad, truncate at end. 



1. Bal^na. Pectoral fin moderate. Head one- third of the entire 

 length. 



I 



