166 PROGRESS IN ZOOLOGICAL KNOWLEDGE xn 



fully appreciated when the elaborate and beautifully illustrated 

 work which Professor Marsh has now in progress is completed. 



The last Linnaean order, CETE, is exactly conterminous 

 with the order so named, or rather more generally modified 

 to Cetacea, in the best modern systems, for Linnseus did not 

 commit the error of Cuvier and others, of including the Sirenia 

 among the whales. His knowledge of the animals composing 

 the group was necessarily very imperfect ; indeed it is only 

 within the last few years, especially since the impulse given 

 to their study by Eschricht o Copenhagen, that the great 

 difficulties which surround the investigation of the structure 

 and habits of these denizens of the open sea have been so far 

 surmounted that we have begun to obtain clear views of their 

 organisation, affinities, and geographical distribution. 



Two most remarkable forms of mammals, so abnormal in 

 their organisation as now to be generally considered deserving 

 the rank of a distinct sub-class, the Echidna and Ornitho- 

 rhynclius, were first made known to science in 1792 and 

 1799 respectively, and consequently have no place in the 

 Systema Naturce. The very recent discovery of a third form 

 to this group, or at least a very striking modification of one 

 of the forms, the large New Guinea echidna (Acanthoglossus 

 'bruyriii}, is the last important acquisition to our knowledge 

 of the class. 



In this brief review of the progress of one small section of 

 one branch of zoological knowledge, it will be seen that it is 

 chiefly of systems of arrangement, of classification, and of 

 names, that I have been treating. By many biologists of the 

 present day these, are looked upon as the least attractive and 

 least profitable branches of the subject. The interest of 

 classification, though it has lost much in some senses by 

 the modern advances of scientific biology, has, however, 

 gained vastly in others. The idea that has now, chiefly 

 in consequence of the writings of Darwin, taken such strong 

 hold upon all working naturalists the idea of a gradual 

 growth and progressive evolution, and therefore genetic 

 connection between all living things breaks down the 

 artificial barriers which zoologists raise around their groups, 

 and shows that such names as species, genera, families, 



