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THE AMEBIC AN NATURALIST [Vol. LIV 



pletely surrounds the hair. The cuticular portion of the 

 hair may be likened to a pile of tall tumblers placed one 

 within the other, the upper rims representing the free 

 ectal edges of the scales. Isolated coronal scales of 

 various types are represented in Figs. 193 to 199. Fig. 

 93 represents a form which may be regarded as one of 

 the simplest of the coronal scales. An isolated scale of 

 this form is also shown in Fig. 193. The numerous varia- 

 tions of this type of scale are usually in the direction of 

 a more flaring and more irregular ectal edge, as can be 

 seen by comparing Figs. 93 to 113, and Figs. 193 to 199. 



The coronal scales may be subdivided into simple 

 (Figs. 93 to 102), serrate (Figs. 103 to 107), and dentate 

 (Figs. 108 to 113). The simple scales, as well* as the 

 serrate are the forms usually found among the bats, 

 which are fairly constant in this regard. Figs. 106 and 

 107 represent, perhaps, the maximum of scale decora- 

 tion among the mammals. These scales, isolated from 

 the cortex, are shown in Figs. 196 and 197. The inter- 

 mediate bat (Mormops intermedia) whose hair is illus- 

 trated by Figs. 107 and 197, possesses, possibly, the finest 

 of mammalian hair. The shafts of the fur hair average 

 6.80 in diameter, and often shafts of as small a diam- 

 eter as 4.30 fi can be found. In these hairs, apparently, 

 the cuticle has become greatly thickened, and the medulla 

 has been lost. This seems to be true of the majority of 

 the bats, more particularly of those bearing the serrate 

 type of cuticular scales. The dentate type of scale is not 

 found among bats, but seems to be scattered among sev- 

 eral orders of mammals. It occurs most frequently 

 among the members of the glires, or rodents. The sim- 

 plest form is shown in Fig. 108, and other typical forms 

 in Figs. 109 to 112. There seems to be not a great range 

 of variation in this type of scale, the majority of species 

 which bear this type of hair approximating very closely 

 to the forms shown in Figs. 109 to 112. Fig. 113, how- 

 ever, shows an anomalous form of scale characteristic 

 of both the American and European species of otter. In 



