JECEMBER 12, 



1890.] 



SCIENCE. 



333 



size, extent of surface, and mode of union, of its component bones. 

 Tliese, in their turn, are correlated with the articulation of the 

 lower jaw, and with the amount of surface presented by the as- 

 cending ramus; with the neighboring fosbse, crests, and processes; 

 with the dental series; and necessarily with the muscles con- 

 cerned in mastication, varied as they are in their action. 



The jugal arch, as it exists in the order of the Carnwora, offers 

 perhaps the most instructive example of the various points to be 

 •considered in its morphology. Take the cranium of the tiger as 

 a type of the oats {Felidm). In this, the arch, composed of three 

 bones, — the squamosal, malar, and maxilla, — presents an extraor- 

 dinary, horizontal curvature, thereby vastly increasing its expanse, 

 giving great width to the temporal fossa, and consequently allow- 

 ing a corresponding development of the temporal muscle, which, 

 taking its origin from the largely expanded surface of the parietal, 

 and from the occipito-sagittal crest, passes forwards and down- 

 wards, to be inserted into the high, wide, oblique, coronoid jiro- 

 cess of the mandible. 



The increase in length of the arch, due to the great horizontal 

 curvature, is also seconded by the advanced position of the orbit 

 upon the skull, and to its height above the level of the articulation 

 of the mandible. 



The vertical curvature of the ai-ch, with the convexity above and 

 the concavity below, denotes increased power of resistance to the 

 strain produced by the muscular fibres of the masseter, which, 

 springing from the under side of the arch, are carried obliquely 

 backward and downward to be inserted into the deeply grooved 

 ascending ramus. The action of the pterygoids, which is similar 

 to that of the masseter, is also relatively powerful. The fibres 

 rising from the pterygoid fossae and plates are inserted into the 

 inside of the angular portion of the lower jaw, and into the neck 

 of the condyle. The sutui'e by wliich the jugal process of the 

 squamosal and the malar are joined extends very obliquely through 

 a greater portion of the arch; this obliquity imparting much 

 strength to the bony structure, and giving force to assist the press- 

 ure upward. 



The convex surface of the transverse condyle of the mandible, 

 received into the deeply grooved glenoid cavity, forms the hinge- 

 like articulation fitted for the vertical action of the jaw, and 

 which is necessary for the prehension, tearing, and division of the 

 flesh by means of the characteristic incisors, canines, and molars. 



In the order of the Edentata, the cranium of the great ant eater 

 (Myrmecitphagus jubata) exhibits a jugal arch which is the extreme 

 opposite of that which has been thus partially described. In the 

 ant-eater the arch is very incomplete, consisting of a short styliform 

 process given off by a very rudimentary jugal, and of an extremely 

 small, tuberous, zygomatic process from the squamosal, no union 

 being formed between the two. There is no post-orbital process 

 of the frontal, and indeed no separation between the orbiial and 

 temppral fossse. Under these circumstances, the muscular de- 

 velopment concerned in the preparation of the food is very feeble, 

 correlated as it is with the entire absence of teeth, and any neces- 

 sity for mastication. 



Between these two extreme modifications there are many inter- 

 mediate forms of the jugal arch. In some of the Rodentia, al- 

 though the arch is relatively weak, as shown by the downward 

 convexity in its vertical curvature, the masseter has other points 

 of fixed insertion, by which means the masticatory powers are 

 fully sustained. Moreover, the antero-posterior form of condyle 

 is received into an undefined fossa situated upon the side of the 

 cranial wall, whereby a corresponding amount of dental energy is 

 imparted, suited to the habits of the rodent. Cope and Ryder 

 have attributed the peculiarities of the denial system in this order 

 to the mechanical consequences of an increase in the length of the 

 incisors, which increase is due to their continued use. By a 

 similar frocess of reasoning it may be shown that the imperfect 

 condition or the arch in some of the other orders is correlated with 

 an entire absence of the teeth, with a feeble muscular energy, and 

 a loss of mastication, all being the result of continuous disuse. 



In short, it may be said in general that the great development 

 of the arch is dependent upon modifications which are strictly 

 due to use, while its weakened and imperfect condition is equally 

 the result of modifications which are due to disuse. 



There seems as yet no evidence affordeil by paleontological re- 

 search to show that the jugal arch has undergone any special 

 changes since the days of the Creodonta, the ancestors of the cats. 

 We may therefore conclude that the phylogenesis of the Caniwora, 

 at least, remains essentially the same, so far as this portion of the 

 skull is concerned. D. D. Slade. 



Cambridge, Mass., Deo. 5. 



BOOK-REVIEWS. 

 A Revision of the South American Nematognathi or Cat-Fishes. 

 By Carl H. Eigenmann, Ph.D., and Rosa Smith Eigenmann. 

 San Francisco, Gal. Acad. Sci. 8°. |3. 



This extensive work will be highly welcomed by ichthy- 

 ologists. It is based on several thousand specimens from the 

 Museum of Comparative Zoology at Cambridge, Mass. The ma- 

 terial was collected chiefly during the Thayer Expedition. Besides 

 that, numerous other collections were studied; for instance, that 

 of Senhor Honorario, made in Goyaz, that made by his Majesty 

 Dom Pedro II in Rio Grande do Sul, and that made in Lake Titi- 

 caca by Professor Alexander Agassiz and Mr. S. Garman. 



In all, 101 genera and 407 species are enumerated. Full de- 

 scriptions of most of the species in the Museum of Comparative 

 Zoology are given. The synonymy is ti'eated in full, and the bib- 

 liography is given at the end of the volume. In this we should 

 like to add Dr. V. B Bruehl's " Osteologisches aus dem Pariser 

 Pflanzengarten "' (Wien, 1856), containing descriptions and figures 

 of the osteology of Aspredo, Loricaria, and Hypostoma. 



Besides the index of species and genera, a geographical index 

 is added, and a map with especial reference to the localities where 

 collections have been made. Both will be of great help to the 

 student. 



The different forms are referred to eight families, seven of 

 which are confined to tropical America. The relationship of 

 families and subfamilies is expressed by a phylogenetic diagram. 



The nearly cosmopolitan family Siluridce (it is only absent in 

 Australia') reaches its greatest development in South America, 

 where it is represented by six subfamilies. The Bunocephalidce 

 are found in the whole course of the Amazon and in Guiana. 

 The Diplomystidoe are represented by a single genus and species 

 from Chili, the Diplomystes papillosus, Cuv. The family Hy- 

 pophthalmidce, with the genera Hypophthahnus and Helogenes, 

 is confined to the northern Amazon and Guiana. The Pygidiidce 

 contain eleven genera, and are found in mountain-streams of 

 Chili and the Argentine Republic. The Argiidoe, the anatomy of 

 which needs further study, have only three genera. They are 

 characteristic of the Andes of Peru, Ecuador, and Colombia. 

 The LoricariidcB, with twenty-four genera, occur east from the 

 Argentine Republic to Central America, west in Ecuador and Co- 

 lombia. The seven genera of the Call ichthy idee extend from La 

 Plata to Rio Orinoco, and in the Amazon as far as Nauta. 



The authors may be congratulated on this work, which will be 

 of the greatest value to the student of fishes. Thanks are due to 

 the California Academy of Sciences for publishing this work. It 

 forms Volume I. of a new series of publications, called " Occa- 

 sional Papers of the California Academy of Sciences." 



AMONG THE PUBLISHERS. 

 '•From Babel to Comparative Philology" is the title of a 

 chapter in Dr. Andrew D. White's " Warfare of Science," which 

 will open the January Popular Science Monthly. It gives the 

 origin of the legend in regard to the great tower and the confusion 

 of tongues, and also traces the early history of the belief that 

 Hebrew was the only language spoken by God and men before 

 Babel was undertaken. The second article in the great series on 

 " The Development of American Industries since Columbus" will 

 also appear in that number. The special topic is " Iron Mills and 

 Puddling-Furnaces," being a part of the general subject of iron 

 and steel, which is being treated by Mr. William F. Durfee. Like 

 the opening paper, it is copiously illustrated, and much more 

 readable than the title would indicate. Professor Huxley has at- 

 tacked the idea that the people who spoke Aryan were one distinct 

 race. His discussion of this point will le printed in the Popular 



