422 



NATURE 



\Augiist 15. 1878 



The twenty-one species at that time recognised of the great 

 group of hollow-horned Ruminants are distributed quite artifi- 

 cially in three genera, Capra, Ovis, and Bos. Though subsequent 

 investigations have greatly increased the number of species 

 known, we are still in much uncertainty about their mutual 

 affinities and generic distinctions. Being a group of compara- 

 tively modern origin, and only just attaining its complete 

 development, variation has chiefly affected the less essential 

 and superficial organs, and the process of extinction of inter- 

 mediate forms has not operated sufficiently long to break it up 

 into distinctly separated natural minor groups, as is the case 

 with many of the older families, which yield, therefore, far more 

 readily to the needs of systematic classification, especially as 

 long as the extinct forms are unknown or ignored. 



'I'he sixth order of land mammals, Bellu^, corresponding to 

 the Pachydermata of Cuvier, contains what is now known to be 

 a heterogeneous collection, viz., the horses, the hippopotamus, 

 the pigs, rhinoceros, and the rodent capybara. The abolition of 

 these two last orders and the entire rearrangement of the ungu- 

 late mammals into two different natural groups, now called 

 Artiodactyla and Perissodactyla, first indicated by Cuvier in the 

 " Ossimens Fossiles," from the structure of the limbs alone, and 

 afterwards confirmed by Owen from comparison of every part of 

 the organisation, has been one of the most solid advances made 

 in our knowledge of the relations of the mammalia during the 

 present century. 



The past history of this, as of so many other groups of verte- 

 brated animals, has been brought to light in an unexpected 

 manner by the wonderful discoveries of fossil remains made 

 during the last ten years in the Rocky Mountains of America, 

 discoveries the importance of which will only be fully appreciated 

 when the elaborate and beautifully illustrated work which Prof. 

 Marsh has now in progress is completed. 



The last Linna^an order, Cv-TJE, 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 of Copenhagen, that the great difficulties which sur- 

 round 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 Ornithorhynclnls, were 

 first made known to science in 1 792 and 1 799 respectively, and 

 consequently have no place in the " Systema Naturae." The very 

 recent discover)' 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 bruijnii), 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 modem advances of scien- 

 tific 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, orders, &c., are 

 merely more or less clumsy attempts to express various shades of 

 differences among creatures connected by infinite gradations, and 

 in this sense destroys the importance attached to them by our 

 pi'edecessors. On the other hand, it immensely increases the 

 interest contained in the word relationship, as it implies that the 

 word is used in a real and not, as formerly, in a metaphorical 

 sense. There is a kind of classification, such as we might apply 

 to inanimate substances or manufactured articles. We may say, 

 for instance, that a tumbler, a wine-glass, and a tea-cup are more 

 closely related to each other than either one is to a chair or a 

 table, and that they might be formed into one gi'oup, and the 

 last-named objects be placed in a second. This kind of classifi- 



cation is certainly useful in its way for methodical arrangement 

 and descriptive purposes. It is the kind of arrangement which 

 Linnaeus and his contemporaries applied to animals. It is, how- 

 ever, a very different classification from that which supposes that 

 the members of a group having common essential characters are 

 descended from a common ancestor, and have gradually, by 

 whatever cause or means, become differentiated from other 

 groups. On this view a true classification, if it could be ob- 

 tained, would be a revelation of the whole secret of the evolution 

 of animal life, and it is no wonder that many are willing to devote 

 so large a share of their energies to endeavour to attain it. 



The right application of the principles of nomenclature, first 

 clearly established by Linnaeus, to the groups we form is, again, 

 by no means to be despised, as laxity and carelessness in this 

 respect are becoming more and more the greatest hindrances to the 

 study of zoology. The introduction of any new term, especially 

 a generic name, and indeed the use of an old one by any person 

 whose authority carries weight, has an appreciable effect upon 

 the progress of science, and should never be done without a full 

 sense of the responsibility inairred. All beginners are puzzled 

 and often repelled by the confused state of zoological nomen- 

 clature to an extent to which those who have advanced so far as 

 only to care for the things, and to whom the actual names by 

 which they are called are comparatively indifferent, have little 

 idea. Those whose special gift or inclination leads them to the 

 pursuit of other branches of biology, as morphology, physiology, 

 embryology, &c., must have definite names for the objects they 

 observe, depict, or describe, and are dependent upon the 

 researches of the systematic zoologist for supplying them, and 

 should not neglect to take his counsel, otherwise much of their 

 work will lose its value. 



Several times has the British Association thought this a worthy 

 subject for the consideration of its members, and through the 

 instrumentality of a committee of working naturalists drew up in 

 1842 an excellent code of regulations and suggestions on the 

 subject of zoological nomenclature. These rules were revised 

 and reprinted in 1865, and in accordance with a resolution 

 adopted at the last annual meeting at Plymouth they have been 

 again republished at the cost of the Association during the pre- 

 sent year. The mere issue of such rules must have had a bene- 

 ficial effect, as they have undoubtedly been a guide to many 

 careful and conscientious workers. Unfortunately there are no 

 means of enforcing them upon those of a different class, and 

 there is still something wanting short of enforcing them, which 

 possibly may be within the power of the Association to effect. 

 In the administration of the judicial affairs of a nation, besides 

 the makers of the laws, we have an equally essential body to 

 interpret or apply the law to particular cases — the judges. How- 

 ever carefully compiled or excellent a code of regulations may 

 be, dubious and difficult cases will arise, to which the application 

 of the law is not always clear, and about which individual opin- 

 ions will differ. The necessary permission given in the Assa- 

 ciation rules to change names which are either "glaringly false," 

 or not "clearly defined," opens the door to considerable latitude 

 of private interpretation. As what we are aiming at is simply 

 convenience and general accord, and not absolute justice or 

 truth, there are also cases in which the rigid law of priority, 

 even if it can be ascertained, requires qualification, and other 

 cases in which it may be advisable to put up with a small error 

 or inconvenience to avoid falling into a larger one. I may name 

 such cases as the propriety of reviving an obsolete or almost 

 unknown name for one which, if not strictly legitimate, has. 

 been universally accepted, or the retention of a name when 

 already applied to a different genus, instead of the institution of 

 another in its place. For instance, should the name Echidna^ 

 by which the well-known monotrematous mammal is known in 

 every text-book and catalogue in every language, be superseded 

 by Tachyglossus, because the former name had previously been 

 applied to a genus of snakes ? or should the chimpanzee be no 

 longer called Troglodytes lest it should be confounded with a 

 wren ? Should Chiromys be discarded for Daubentonia, Triche- 

 chus for Odobinus, and Tapirus for Hydrochcerus ? Should the 

 Java slow lemur be called I.oris, Stenops, or Nycticebus ? Should 

 Sowerby's whale be placed in the genus Physetcr, Delphinus, 

 Delphinorhynchus, Heterodon, Diodon, Aodon, Nodus, Ziphms^ 

 Microptei-us, Micropteron, Mesodiodon, Dioplodon, or Mesoplodon,. 

 in all of which it may be found in various systematic lists? 

 Should one of the largest and best known of the Cetaceans of 

 our seas be called Balcenoptera muscuhis, Physalus anhqtwrum, 

 or Pterobalcena commtims, all names used by authors of high 



