1883.] 229 [Jeffries. 



vascular and supplied with abundant lymphatics, as shown by 

 Kostarew (21), for combs, and as I have myself seen in the wattle 

 of turkeys. Both structures owe their color to the flow of blood. 

 The lateral flaps, or ears of the Guinea hen, on the other hand, 

 have a bright pigment, and the cutis vera is very compact. 



The comb of hens is developed as a simple fold of the skin, and 

 involves all the layers of the epiderm. After hatching the outer 

 layers are shed, as in the rest of the body. The first steps are 

 often visible by the eighth day. 



SPUES. 



Spurs, of which those of the cock will be taken as an example 

 occur in various groups and in various places. Where they occur 

 they are composed of a bony core, which is covered by the cutis 

 vera and epiderm ; the bone being attached to subjacent skeletal 

 bone. The epiderm is just like that of a claw. 



The first signs of the spur appear about the tenth day of incu- 

 bation. At this stage it is simply a disc of the same structure as 

 the surrounding scuta but not forming a fold. In the histology 

 of the developing epiderm (fig. 26) a spur is precisely like a 

 scutum, claw, or mandibular coat. The distinction lies solely in 

 the shape, which becomes little by little slightly hemispherical, by 

 the thickening of the cutis vera. After birth the bony core is 

 formed by ossification in the cutis vera from one or more centres. 

 The bony core thus formed later on anchyloses with the tarso- 

 metatarsal bone ; so the spur is in origin purely dermal. 



TOE PADS. 



The pads on the palmar surface of the toe are of interest, since 

 they have peculiar functions and structures. They are papillae 

 or mounds of the skin packed close together and consequently 

 polygonal. The result is, that the sole of the foot is quite rough, 

 and admirably adapted for grasping. On the sides of the foot, more 

 especially of the toes, they gradually pass over into the scuta. 

 There is no hard and fast line between the two, yet the well de* 

 veloped pad never forms a flap, while the scutum always does. 



The peculiar points in their structure are the papillae of the 

 cutis vera, which extend into the epicterm in the same manner as 



