APPENDIX. 



Pending the publication of a revised monograph of the iuseetivores of 

 the United States (which will probably be soon undertaken in part at 

 least by Dr. Elliott Coues), a list of those works in which the most re- 

 liable information respecting various species may be found will perhaps 

 be acceptable. In addition to the works already cited in the foot-notes 

 to the preceding paper, the following will be the most serviceable, and 

 therein references to various other sources of information can be found. 



The distinctive characters of the families Soricidse and Talpidse — the 

 only ones represented in the North American fauna — are also contrasted 

 in detail ia parallel columns, and their common characters extended 

 across their respective columns. 



The tables thus given are extracted from the series prepared to bring 

 the points of agreement and disagreement of the several families of 

 Insectivora into more prominent relief. 



So far as the Soricidoe are concerned, the characters common to all 

 their known members might be extended almost indefinitely ; but with- 

 in the limits of the family Talpidse, as here accepted, the range of 

 variation is much more considerable, and the purpose here being simply 

 to exhibit those characters in which all the members of one family 

 differ from all those of the other, the features not answering for this 

 purpose are eliminated from the comparison. It is probable, however, 

 that the contrast might be extended considerably more than has now 

 been done, but there are several genera which have not yet been de- 

 scribed in sufficient detail to permit a more extended exhibition of the 

 common characters to be given. 



The descriptions thus contrasted have been generalized from a com- 

 parison of skeletons and skulls of the American and European types of 

 the superfiimily. The only genus of the Talpidse so represented of 

 which I have not been able to examine the skeleton is TIrotrichus ; of 

 that form I have only had the opportunity of seeing the very imper- 

 fect skull which nearly twenty years ago served Professor Baird as the 

 type of his Urotrichus Gibbsii, the attempts since made to obtain other 

 examples of the species not having been successful. 



At the same time, it must not be disguised that the differential char- 

 acters offered by the two families here distinguished are very numerous 

 and salient, and the common characters comparatively few. It may 

 therefore be an open question whether the two should not be elevated to 

 the rank of " superfamilies" (" Soricoidea '' and " Talpoidea") : the writer 

 will only urge in favor of the valuation here assigned, the apparent closer 

 unity between the two than between either and any other family of 

 insectivores and the importance and significance of the common char- 

 acters furnished by the agreement in the structure of the molar teeth ; 

 from the point d'appui thus secured, the appreciation of the respective 

 characters of the two groups seems to be facilitated, and though the 

 differences are many the agreements are more numerous than in com- 

 parison with any other form, and are likewise supported by coincidences 

 which may be of little account by themselves, but in the aggregate be- 

 come quite significant. 

 5 c 



