114 



KNOWLEDGE 



[April 1, 1890. 



now found, constituting, as they do in many cases, a large 

 proportion of tlie stratum in wliich they are preserved. 



No classification of the animal kingdom can be re- 

 garded as more than a temporary convenience, for the 

 rapid advance of biological knowledge will soon render 

 some modification necessary. It is not surprising, there- 

 fore, to see important changes in the tabular view of the 

 animal kingdom given at page 87. The sponges, having 

 been shown to possess a more complex organization than 

 is found in any true Protozoan, are placed in a separate 

 sub-kingdom, the Porifcra, thus keeping them distinct 

 from both Protozoa and Cwlenterata. The Ascidians, or 

 Tunicata, are now placed next to the Vertebrata. The 

 Odontornithes or Toothed birds of North America are no 

 longer kept as a distinct group ; but those with a raft-like 

 breast-bone are placed in the Ratitae, and those with a keel 

 to the breast-bone are included in the Carinatse. 



Another change, of a dift'erent character, but of no 

 little importance, is the use of black letters and varied 

 types for the headings and different groups ; by this 

 means the eye is much assisted, and the arrangement is 

 more clearly impressed on the mind. 



In a work dedicated especially to fossil forms, space 

 could not be spared for a very full description of recent 

 types ; nevertheless, the authors have given such an 

 account of the general structure of each group that the 

 subsequent descriptions of the different forms are perfectly 

 intelligible. 



It is pleasing to find that Dr. Nicholson is not one of 

 those who are given to change ; at least, he has retained 

 the tune-honoured and expressive term Lamellibranchiata, 

 rather than use the less satisfactory name which has 

 obtained favour with some Malacologists. The Ammoni- 

 tidae are at present in a transitional stage, and much 

 work has yet to be done before their grouping can be 

 settled. The Ammonites, however, are among the most 

 important fossils found in the Secondary rocks, for the 

 determination of zones of life, and have been used for 

 this purpose with good results in marking the lesser 

 di\isions of the Lias and other formations. 



The restorations of ganoid fishes given in the early 

 jjart of the second volume are very instructive, and being 

 mostly from the hands of masters in Ichthyology may be 

 depended upon as embodying facts of nature ; more espe- 

 cially may be noted the figures of rtcrichtlii/x, of Chnnilros- 

 teii.i, and of Pahifcmiscus, which are the result of much 

 patient work on the part of one of our most eminent 

 pala'ichthyologists. Dr. E. H. Traquair. 



Mr. Lydekker has been much occupied of late among 

 the fossil Eeptilia, and we here find an embodiment of his 

 own labours and those of other workers both in this 

 country and abroad. The discovery some few years ago of 

 almost perfect skeletons of iguanodons in the Wealden of 

 Belgium, and their exhibition in the Brussels Museum, 

 lent a new interest to the more fragmentary remains found 

 in Britain, some of which belong to forms identical with 

 the Belgian species. It is, however, in America that the 

 most remarkable dinosaurs have been found, some of them 

 being of gigantic size. According to Prof. Marsh, 

 Brnnto.tfinnis was about 50 feet in length, -ndth a footprint 

 covering nearly a square yard, while its weight must have 

 been more than twenty tons. Another of these creatures, 

 named Atlantosnurm, seems to have been even larger than 

 this. E^^dence of forms allied to some of these American 

 giants, but apparently not so large, has been found in the 

 Wealden of this country. 



The remains of fossil birds are not numerous, but some 

 have an exceptional interest. The Airliaopti'i-i/.r, from the 

 lithographic slates, remains the oldest, as it is the most 



primitive type of bird yet discovered. Additional evidence 

 has of late years been forthcoming that gigantic birds, 

 equalling in size some of the larger forms of the New 

 Zealand Dinoinis, lived in Britain, as well as on the Con- 

 tinent and in North America, in early Eocene times. 



The genus Mirnlestcx, as represented by isolated teeth 

 from the Trias of Wiirtemberg and of England, has for 

 long been the only luiown mammal from beds of so early 

 a date ; but Sir Kichard Owen has now described a re- 

 markable skull, from beds of about the same age, in South 

 Africa, which he has named Tritijlodim. This has multi- 

 bercular molars, accompanied by large incisor teeth, and 

 it is believed to have belonged to a low type of mammal. 



Special attention is directed by the author to the 

 genealogy of the horse, as one of the best instances of 

 e\'olution among the higher mammals which has yet been 

 worked out. The gradual changes in the pattern of the 

 teeth and the increase in the number of digits, are traced 

 from the recent horse with one functional toe and two 

 splint bones, through Hiiipariim with its three digits, two 

 of which are small, and Aiu-liitherium, with three digits 

 all reacliing the ground, to Hi/raaitheriraii, with its four 

 functional digits of approximately the same size, the last- 

 named animal occurring in the lower Eocene. 



It is imiwssible here to discuss the hypothesis advocated 

 by Mr. Lydekker, that the horses of America and Europe 

 liave been independently developed in the two countries 

 along parallel but distinct lines ; but this certainly seems 

 less in accordance with kno^Ti facts than does the suppo- 

 sition that from early Eocene times until the Pliocene 

 period there were frequent, if not continuous, opportunities 

 of intercommunication between the northern parts of 

 Europe, Asia, and America. 



The jjonderous IHiioci'mta from the Eocene of Wyoming, 

 are remarkable mammals of a primitive type, seeming to 

 combine the characters of several living forms. The skull 

 of one of these, the V intathetium , has been chosen as 

 an illustration for the cover of the second \olume ; and 

 certamly its form is striking enough, with its six horn- 

 like protuberances from the frontal and nasal regions, and 

 its enormous canine teeth, reminding one of those in the 

 carnivorous genus MdclKirodua. 



The fourth part of this manual, which treats of 

 Pala?obotany, has been much improved ; but it professes to 

 be only a general summary of the subject, and is not 

 treated in so detailed a manner as the prenous parts. 



The work is throughout profusely illustrated, and the 

 figures are for the most part good and well chosen ; but 

 some of them are far from bemg creditable productions, 

 and it is a pity they ha^■e been allowed to mar the general 

 excellence of the work. As an example of what woodcuts 

 may and should be, see that on page 12G5, and for an 

 example of what they should not be, see page 1283. A 

 few of the figures are misleading, such, for instance, as 

 the mouth of the sturgeon on pages 916 and 975, and the 

 old figure of a Pterodactyl, on page 1203, with four 

 clawed digits to the manus, will lead to more errors than 

 will be rectified by the explanation and correction in the 

 text. These defects, however, are small when compared 

 with the general excellence displayed throughout the two 

 volumes, which contam a large amount of reliable infor- 

 mation, brought together in a convenient and readable 

 form ; information which would otherwise have to be 

 sought in many separate treatises, often difficult of access. 

 The work, therefore, may be confidently recommended to 

 all who desire a thorough insight into the study of fossils ; 

 and moreover, although ten years have elapsed since the 

 publication of the prenous edition, this remains the only 

 English manual of Pal<T?ontology. — E. T. Newtox. 



