104 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxn. 



HABITS. 



In common with most other l)ats the habits of the Hemidermas are 

 not well known. Charles Darwin writing of II. perspicillatum^ says: 

 "On entering an old limekiln in the middle of the day 1 disturbed a 

 considerable number of them; they did not seem to be much incom- 

 moded by the light, and their habitation was much less dark than that 

 usually frequented by these animals." The eaves of houses and attics 

 are not infrequently chosen as roosting places, though caves and hol- 

 low trees are also utilized. A collector who obtained some of these 

 bats for the U. S. National Museum in northern Ecuador has recorded 

 on his labels that some of the specimens were taken "under stones in 

 the ditch." Another collector smoked more than a hundred bats of 

 several species out of two hollow trees on the Tesechoacan River in 

 Vera Cruz, and among the numl)er were sixty-eight specimens of the 

 form II. j>. aztecum. Mr. E. T. Giers, who collected in Trinidad, 

 records that these bats "roost in houses — bite animals." Whether - 

 this last observation is correct I am unable to say. 



The breeding period is somewhat extended and probably lasts 

 through half the year or even more. Messrs. Nelson and Goldman 

 took half -grown individuals and pregnant females of H. j). aztecmn at 

 Tuxtepec, Mexico, on April 12 and 22, and half-grown young at the 

 same place on October 21. In Ecuador young were taken at an eleva- 

 tion of 3, 500 feet on March 11, while females containing small embryos 

 and individuals three-fourths grown were taken at Trinidad on June 13. 

 Nothing is known of the habits or breeding season of the smaller spe- 

 cies siihrufum and castaneum. 



The young acquire many of the adult characteristics very early and 

 measurements can not be relied upon to determine age. Measure- 

 ments for a specimen from Vera Cruz (Cat. No. 123761, U.S.N.M.), 

 which appears to be only a few daJ^s old, are as follows: Hind foot, 

 13 mm.; forearm, 37; tibia, 17; ear, 18; nose-leaf, 7; thumb, 12. 

 The milk-dentition is just coming into place in the upper jaw, while 

 in the lower jaw none of the teeth have cut the gum, though the 

 canines and first premolars are visible through it. 



VARIATION. 



The variations within the several species of the genus are consider- 

 able and affect practically all of the characters. Color variations are 

 so great as to almost exclude the value of color for specific deter- 

 mination. In one form {II. p. aztecmn) the color ranges from dull 

 sooty black to a bright ferruginous. In the other forms the observed 

 variations are not quite so great. Considerable variation is also found 



« Under the name of Phyllostoma grayi Waterhouse, Mammalia of the Voyage of 

 the Beagle, 1839, p. 3. 



