108 PROCEEDINGS OF THE NATIONAL MUSEUM vol. no 



shortening of the'^rostrum and lack of dental specialization (loss of 

 teeth and cusps) . In these features the resemblance of Euderma and 

 Plecotus to Myotis is greater, to Pipistrellus less. This relation is 

 further substantiated in the postcranial skeleton, where Euderma and 

 Plecotus have some characters of Myotis (species compared: lucifugus, 

 thysanodes, yumanensis) , and some of Pipistrellus (species compared: 

 javanicus, subflavus) , but in most features they are more like Myotis. 

 On the basis of dental, osteological, and external features, it appears 

 that Euderma and Plecotus should stand between Myotis and Pipi- 

 strellus in the classification of Chiroptera. 



Genus Euderma: Euderma maculatum is more specialized than any 

 species of Plecotus. It has carried auditory modification — the most 

 spectacular character of the two genera — to the greatest extreme, 

 and in dental characters it is unique. By elongation, in addition to 

 enlargement, of the auditory bulla it has departed from the usual 

 vespertilionid pattern. Externally too, Euderma has exceeded Plecotus 

 and, indeed, all other vespertilionids in auditory specialization — in 

 extreme enlargement of the auricle, in the simplification of the tragus 

 by elimination of the posterior basal lobe, and in the attachment of 

 the tragus to the posterior basal lobe of the auricle as well as to the 

 anterior basal lobe so that the auricle forms a more perfect funnel 

 to the auditory meatus. 



Hall (1934) pointed out important differences between the body 

 skeletons of Euderma and Plecotus. Notable are the unusual length 

 and shape of the presternum and the shape and angle of the acromion 

 process of the scapula in Euderma. 



The anterior portions of the tooth rows show great specialization 

 in Euderma. In the upper jaw I' and P^ are reduced; in the lower the 

 canine is reduced (though provided with a prominent accessory cusp), 

 P3 has been eliminated, and P4 is single-rooted. The posterior portions 

 of the tooth rows, on the other hand, are morphologically primitive in 

 character: There is a trace of a hypocone cusp on M^ and on M*, the 

 metacone of M^ is well developed, and P4 has a metaconid cusp. With 

 the exception of the elongated brain case and bifid median postpalatal 

 prominence, other features of the cranium are primitive as far as the 

 genera Euderma and Plecotus are concerned: The rostrum is weak, the 

 supraorbital region is sharply ridged, the temporal ridges do not 

 coalesce, and the zygomata are strong and are provided medially with 

 a large postorbital expansion. 



The nostrils are unspecialized, retaining the primitive basic vesper- 

 tilionid shape, as seen in Myotis and Pipistrellus. 



The evolutionary significance of the bold black and white color 

 pattern of the fur is not known. Such a pattern crops up sporadically 

 in the orders of the class Mammalia, but is notably rare in Chiroptera. 



