Five skins with skulls of Rhogeëssa, collected by J. R. Alcorn in thestates of Sonora and Nayarit of western Mexico, were recently receivedat the Museum of Natural History of the University of Kansas. Two otherspecimens of the same genus, collected by Walter W. Dalquest in thestate of Veracruz of eastern Mexico, also are in the Museum of NaturalHistory. With the aim of applying names to these bats they were comparedwith materials in the United States National Museum (including theBiological Surveys collection) where there are approximately the samenumber of Mexican specimens of Rhogeëssa as are in the Museum ofNatural History.
The three kinds of Rhogeëssa named from Mexico are as follows: R.parvula from the Tres Marias Islands off the west coast of Nayarit; R.tumida from Mirador, Veracruz, on the eastern slope of the Republic;and R. gracilis from Piaxtla, Puebla, on the southern end of theMexican Plateau.
Of Rhogeëssa gracilis Miller (N. Amer. Fauna, 13:126, October 16,1897) only three specimens are known; two are from Piaxtla, Puebla, andthe third is from the Isthmus of Tehuantepec. Only the specimen from theIsthmus has a complete skull. The broken skull of the holotype is partlyseparated from the skin of the head and in such a manner as to revealthe teeth. The skull of the holotype seems to be broader (relative toits length) across the mastoids and posterior parts of the zygomata thanin R. tumida or than in R. parvula. My comparisons indicate thatRhogeëssa gracilis has larger (longer and wider) ears than R.parvula and R. tumida and that it is specifically distinct from thetwo last mentioned kinds.
The two other nominal species from Mexico, R. parvula and R. tumida,were named and described by Harrison Allen (Proc. Acad. Nat. Sci.Philadelphia, 1866: 285 and 286, respectively) on the basis of threespecimens in the United States National Museum. Two were from the TresMarias Islands and were the basis of the name R. parvula; the thirdwas from Mirador, Veracruz, and was the basis[Pg 230] of the name R. tumida.These specimens seem to have been preserved in alcohol. I have examinedthe skulls of two of these. One (U.S.N.M., new number 37329, old number7842) is alleged to be the paratype of R. parvula and the other(U.S.N.M., 84021) is alleged to be the holotype of R. tumida. In theglass vial containing skull No. 84021, there is a label in thehandwriting of Gerrit S. Miller, Jr., bearing the following information:"In the orig. descr. the number of this sp. is said to be 8195. This isan error. Specimen catalogued 3.1.98 G.S.M. Jr." On the back of a secondlabel in the skull vial there is w