vShufei.dt on the Osteology of Cinclus Mexican/is. 2IC) 



particularly to those whose aim it is to pursue the study more than 

 "skin deep." 



In the adult Dipper the pelvic limb, as far as its skeleton is 

 concerned, is made up of the most usual number of bones ; the 

 thigh having the fenm)\ the leg the tibia and Jibula^ a patella^ 

 the tarsus the bone tarso-metatarsiis^ and finally a foot arranged 

 upon the plan of four toes, with first, second, third, and fourth 

 digit composed of 2, 3, 4, and 5 joints respectively. 



I have already said that these bones are non-pneumatic, they 

 are also of lengths proportionate to the size of the bird, the 

 claws being curved about as much as the}' are in a typical Thrush. 

 Anatomists have described certain general points for examina- 

 tion on these long bones composing the leg ; manv of these are 

 present, but we shall only call the student's attention to a few of 

 them, so as to make clear what we have to point out hereafter. 

 Nothing of striking variance marks the femur, as distinguishing 

 it from the common form of the bone among birds of this class. 

 The same might be said of the tibia, but we must note the two 

 large flaring processes at the anterior and upper end of this, the 

 larger bone of the leg ; in this bone, too, the condyles are well 

 develo2:)ed below. The tarso-metatarsus^ or the bone of the tar- 

 sus, we observe in the old bird, has rather a slender shaft, pre- 

 senting for examination at its upper end the usual dilatation, 

 crowned by a smooth, undulating surface to articulate with the 

 tibia ; behind this, at the same end, we find a tuberous process 

 that has given comparative anatomists no little trouble to name ; 

 but we will speak of this further on. The low'er end of the tar- 

 so-metatarsus has the little lateral facet for the diminutive first 

 tarsal bone, and the three trochlea? for the other toes. 



Let us now, after this brief survey of the bones in the adult 

 take up the young of this species. We find first that the femur 

 has gi"own in the usual manner, its lower end bearing the two 

 large condyles has been formed by one epiphysis which included 

 both of these articulate surfaces. Nothing of particular interest 

 is to be observed in the development of the fibula or the small 

 "splint bone" of the leg. The superior end of the tibia has 

 been formed by the epiphysis including the two large processes 

 that I spoke of above. These plates are called the procnemial 

 and the ectocnemial processes, the inner and outer one respect- 

 ivelv. Thev are turned slightly outwards, springing abruptly 



