638 BULLETIN UNITED STATES GEOLOGICAL SUKVEY. 



tions with the determination of faanal areas. At present, I am inclined 

 to follow Professor Baird in the appreciation of this character. 



Certain other relative proportions of the anterior lateral teeth of the 

 Shrews, which Professor Baird used as means of pushing the analysis 

 of the species still further, seem to be of decidedly less applicability, 

 even if they do not fall wholly within the limits of individual variation 

 of particular specimens examined. These, therefore, I shall not bring 

 into consideration of the question. 



I may add here that no American Shrew is known to possess fewer 

 than 28 or more than 32 teeth, though various authors have miscounted 

 from 26 to 36, in the one case overlooking a minute premolar, in the 

 other counti-ng tho posterior cusp of the upper anterior incisor as a 

 distinct tooth. Genera have been founded on each of these blunders. 



§ 4.— GEOGRAPHICAL DISTRIBUTION OF THE AMERICAN 

 SPECIES OF SOBIGIDJE. 



Shrews have been commonly supposed, or tacitly represented, to be 

 wanting in the warmer parts of America. Many years ago, however, 

 J. E. Gray named two species of " Corsira" from Central America, and 

 I have specimens from different localities in Mexico and from Costa 

 Rica, whence only one* species has hitherto been described. No repre- 



* Blarina (Soriciscus) micruea, Coues. 



Corsira tropicalis, Gray, P. Z. S., 1844, . . . . , descr. nullA (flde E. E. Alston in epist.). 

 Sorex micrurus, Tomes, P. Z. S., 1861, 279 (Guatemala, coll. Osbert Salvin). 



Hab. — Guatemala (Salvin). Costa Rica (Carmiol). 



This is a 30-tootliecl Blarina (subg. Soridscus), very closely related to United. States 

 species like B. cinerea, B. exilipes, and B. herlandieri, if really distinct. As I have not 

 finished my examination of the specific differentiation of this group, I should not here 

 notice the supposed species were it not already described and did I not wish to indicate 

 its proper generic and subgeneric position. 



A short time ago I sent a number of Shrews to my valued correspondent Mr. E. R_ 

 Alston, of London, begging him to compare them with the types of certain species 

 preserved in the British Museum. I receive his answer just in the nick of time, as 

 these sheets are passing the press. He identifies my British American specimens with 

 types of Sir John Richardson's species described in the F. B-A., so that this matter 

 "will be placed beyond dispute as soon as I get ready to use the important information 

 thus kindly communicated by Mr. Alston. 



Among the Shrews sent to him was a specimen from Costa Rica (coll. J. Carmiol), 

 of which he states: — "I have little or no doubt that it is the same as Sorex micrurus 

 Tomes .... I have not access to Mr. Tomes's types, but I have examined another of 

 Mr. Saivin's specimens, in spirits, and have no doubt your animal is the same. I also 

 believe that Gray's Corsira trojricalis is the same, though the types look dai;ker from 

 dirt." 



Mr. Alston writes further: — " Gray's C. iemlyas, afterward renamed in MS. C. feculyas 

 is a large species, apparently a true Sorex . . . ." Not to anticipate the description of 

 the species, which I trust we shall have from Mr. Alston in due time, I thus merely 

 allude to the apparent presence of Sorex proper in Central America, as the Soricidw 

 have not hitherto been ascertained to be represented there excepting by the genus 

 Blarina, nor indeed south of the United States excepting by Blarina and by the beyond- 

 described new subgenus and species of Sorex. 



