VERTEBKATE ZOOLOGY. 



By Professor THEODORE GILL, 



Of Washington, D. C. 



INTRODUCTORY. 



The usual activity has been manifested during the past 

 year by laborers in the different fields of Vertebrate Zoolo- 

 gy. Memoirs have been published on the Morphology and 

 Comparative Anatomy of different systems and parts, many 

 articles have been devoted to Faunal Zoology, and numer- 

 ous new species have been described, although of the latter 

 fewer, perhaps, have been made known than on the average 

 have been introduced during past years. The tendency to 

 admit a wider range of variation, and to refuse specific rank 

 to slight differences is becoming general, and this will oper- 

 ate in future to diminish the number of new species as well 

 as to degrade many old ones. A notable example of the 

 difference now from the past in the mode of treatment of 

 variations has been recently furnished by memoirs of Messrs. 

 J. A. Allen and E. R. Alston on the Squirrels of the Tropical 

 Regions of America. According to Mr. Alston, no fewer 

 than fifty-nine (59) specific names have been at one time or 

 another proposed for forms occurring in the region in ques- 

 tion ; but these have now been reduced by Messrs. Alston 

 and Allen, after independent examination of very rich ma- 

 terial and of almost all the previously described types, to 

 twelve species. 



In the richness of the material at hand, it has not been 

 easy to select that which might be regarded as of greatest 

 value or interest from the mass of contributions to Verte- 

 brate Zoology during the year. Abstracts have been chief- 

 ly made of those memoirs which are of special interest on 

 account of the relations of the facts which they exhibit to 

 problems of morphology, or from the light they throw on 

 homologies ; of those whose interest is inherent by reason 

 of the popularity or well-known character of the animals in 



