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NORTH AMERICAN FAUNA. 



Genus RHOGEESSA H. Allen. 



1866. Eliogeessa IT. Alleu, Proc. Acad, Nat. Sci., Pliila., p. 285 (genus). 



1873. Khogdessa Marscliall, Nomenclator Zoologicns, Mamm., p. 11. 



1878. Ilhogc'cssa Dobson, Catal. Cliiroptera Brit. Mus., p. 245 (subgeiuis of ' Ves^wrugo'). 



1893. Bhogeiissa H. Alleu, Monogr. Bats N. Am., p. 132 (geuus). 



Type species. — Bhogecssa tumida H. Alleu. 



Geographic distribution, — Tropical Mexico, 

 Central America, and probably northern South 

 America (known from Margarita Island, Yene- 

 zuela). 



Generic characters. — Dental formula : 



1-1 



1-1 



1-1 



3-3 



30; 



^'3=3 ' 'T-V ^ ' 2-2' '3-3 

 lower incisors crowded, the outer cusp of first 

 and second obsolete; third lower incisor greatly- 

 reduced in size, unicuspidate (figs. 37 a and 38 a) ; 

 upper incisor very close to canine or in contact 

 with it; skull small, light, and i)apery, narrow 

 and deep; external form variable, but tragus 

 always straight or bent backward, and tail in- 

 cluded to tip in interfemoral membrane. 



RemarlxS. — The genus Hhogeessa has received 

 varying treatment. It was originally described 

 as a full genus whose relationships were sup- 

 posed to be with JSfycticeius and Nyctinoimis. 

 In 1878 Dobson referred it to ^Vesperugo^ as a 

 subgenus. This view has been adopted by 

 most subsequent writers except Mr. Oldfield 

 Thomas and Dr. Harrison Allen, both of whom 

 have recognized Bhogecssa as a 

 full genus related more closely 

 to Nycticeius than to any of the genera usually included 

 under the name ' Vesperiigo.'' Mr. Thomas has pointed 

 out characters in which Rhogeessa resembles Antro- 

 zons. These characters, the reduced size of the outer 

 lower incisor and slightly crenulate posterior border 

 of tragus, seem to be instances of parallel develop- 

 ment rather than indications of genetic relationship. The genus 

 Rhogeessa is closely related to Nycticeius^ but the peculiarities of the 

 lower incisors and the general form of the skull are enough to warrant 

 its recognition. 



Fig. 37.— Left mandibular in- 

 cisors of (a) Rhogeessa and 

 (&) Nycticeius (x20). 



YiG. 38.— Crowns of in- 

 cisors of right mandi- 

 ble of (a) Uhogeessa 

 and (6) Nycticeius 

 (X20). 



