116 PROCEEDINGS OF THE NATIONAL MUSEUM vol. ho 



baculum of P. townsendii as being similar to that of P. rqfinesquii. 

 Pearson, Koford, and Pearson (1952, p. 281) noted that the subgenera 

 Plecotus and Corynorhinns "possess in common two pairs of Cowper's 

 glands, a feature not found in other vespertilionids. Likewise, 

 seminal vesicles apparently are lacking in both of these genera [sub- 

 genera]." 



Of all the morphological features distinguishing the species of 

 Plecotus, those of the muzzle and external ears have been supposed to 

 be of the greatest taxonomic signiiicance. 



Enlarged muzzle glands in P. townsendii protrude as grotesque 

 lumps two to three millimeters high on either side of the muzzle 

 (jBg. 7). There are similar glandular areas on the muzzle of P. auritus, 

 but they do not project as in P. townsendii. They may not be con- 

 spicuous in P. phyllotis; there is no external trace of them on three dry 

 study skins. Dalquest and Werner (1954, p. 156) have observed that 

 the facial glands of P. rafinesquii are histologically similar to those of 

 other vespertilionids, particularly Myotis and Pipistrellus. The 

 prominent muzzle glands (or ''nose lumps") are solid masses of skin 

 covered sebaceous glandular tissue. There are in addition, in 

 the facial area, nests of sebaceous glandular cells, sudoriferous glands, 

 and a sublingual gland of the mucous type. The submaxillary gland 

 apparently has been forced out of the facial area by the extensive 

 development of the other glandular tissues. 



A peculiar posterior elongation of the nostril in P. auritus gives the 

 nostril a crescentic shape (fig. 8). The cornu surrounding the narial 

 opening is slightly reduced from the primitive vespertilionid condition, 

 as seen in Myotis and Pipistrellus, and there is a conspicuous shallow 

 basin extending posteriad from the posterolateral corner of the 

 opening and separated from it by a septum. A similar posterior 

 elongation of the nostrU in P. townsendii is partially concealed by the 

 overlapping muzzle glands. In this species the cornu is reduced to 

 the point of obliteration, and the narial opening is squarish in outline 

 and is bordered by smooth pale-colored sldn resembling the lining of 

 the nostrU. As in P. auritus, the narial opening proper and the 

 posterior elongation are separated by a septum. In the available 

 specimens of P. phyllotis the nostrUs appear to approximate the 

 primitive vespertilionid type, with full cornua and without posterior 

 elongations. 



The snout is truncate in P. auritus and P. townsendii rather than 

 acute as in Euderma maculatum and most other vespertilionines (pos- 

 sibly acute in P. phyllotis) . 



A lappet projecting over the forehead from the anterior base of the 

 auricle is the chief characteristic of P. phyllotis. This appendage is 

 an enlargement of the accessory anterior basal lobe of the auricle (fig. 



