ZOOLOGY. 365 



into its two layers, both imi)ly that the side organs had for ages ex- 

 isted as mere " nerve hills," or nerve epithelium, projecting into the 

 water, and this renders our idea not only x)0ssible but i)robable. In 

 the course of evolution of the ear, the first differentiation of structure 

 that occurred may have been as follows : Certain of these areas of 

 nerve epithelium or sensory macular may, for functional specialization 

 have become inclosed in canals. Now, for still greater specialization, 

 the whole area containing the canals, with perhajis one or two maculre 

 not yet inclosed, may have undergone a general process of involution, 

 and thus given rise to the vestibule and semi-circular canals." 



FISHES, ETC. 



NOTEWORTHY WORKS, ETC. 



The classes of Leptocardians, Marsipobranchiates, Selachians, and 

 Fishes are still so generally considered together under the old designa- 

 tion of Ichthyology that it is convenient in practice for the present at 

 least to recognize this grouping. The number of men deserving of scien- 

 titic consideration who would now refuse the term of classes to at least 

 three of those groups, however, is very small. 



Among the general works on " Ichthyology," thus understood, that 

 have been published during the past year or two, are "An Introduction 

 to the Study of Fishes," by Dr. A. Giinther, and parts relative to Ich- 

 thyology of the general works on natural history of Brehm's "Allge- 

 meine Kunde des Thierreiches ; andCassell's Natural History (by H. G. 

 Seeley). The influence of Dr. Giinther is exhibited not only in his own 

 work, but in the others noticed, and it is with regret that we have to 

 add that influence has been for evil and to propagate and continue in- 

 definitely some of the most unsound ideas and systematic essays that 

 have emanated from any worker in zoology. 



The geographical distribution of fishes in general has been treated of 

 by L. Tillier. The species collected by the Challenger expedition have 

 in part (the shore fishes) been enumerated, and the new ones described 

 and illustrated, by A. Giinther ; Arctic species have been reported on 

 by E. Collet, C. Liitken, and T. Bean ; North American species have 

 been described by D. S. Jordan, C. H. Gilbert, G. B. Goode, E. D. Cope, 

 W. N. Lockington, &c. ; those of South America by F. Steiudachner ; 

 Australian species by Castelnau, H. Jouan, C. B. Klunzinger, «S:c. j 

 African species by C. Dambeck, &c. 



The transformations which fishes undergo after exclusion from the 

 egg have been studied by C. Liitken and C. Emery. 



The temperature of the blood in a considerable number of species has 

 been ascertained by J. E. Kidder. His observations are noteworthy on 

 account of the modifications which they necessitate in the statements 

 respecting these animals current in the books. 



