576 



Comparative Morphology of Chordates 



Fig. 444. Diagrammatic longitudinal sections through the distal ends of the 

 digits of (A) Echidna, (B) an unguiculate mammal, (C) man, and (D) a horse 

 (1-3) Phalanges; (b) torus; (N) nail-plate (unguis); (S) sole-horn (subunguis); 

 (W) bed of claw or nail. (After Gegenbaur and Boas, from Wiedersheim [Parker]: 

 "Comparative Anatomy of Vertebrates." By permission of The Macmillan Com-, 

 pany, publishers.) 



Fig. 445. History of antler of deer (Nitsche in Weber). (A) First appearance of 

 spike on frontal bone. {B) Skin retracted from spike, latter with resorption sinus at 

 base. (C) Loss of spike. (D, E) Stages of development of antler of second year; 

 covering of pedicel with skin; outgrowth of antler, continued in (F) with axis and 

 tine of new horn shown, all covered with skin and hair ("velvet"). (G) Skin lost 

 from antler, (c) Dermis; (e) epidermis with hair; (/) frontal bone; (s) spike; (/) tine; 

 (1, 2) antlers of first year and second year. (Courtesy, Kingsley: "Comparative 

 Anatomy of Vertebrates," Philadelphia, The Blakiston Company.) 



