154 On the Tarsus and Oarjms of Birds. 



In regard to the reptilian characters iu birds, it seems tliat 

 a nearer relation between birds and pterosaurians can be 

 established, with the additional carpals pointed out in this 

 paper. At least one of the characters for separating the 

 pterosaurians from the birds, as given by Owen, fails in 

 the light of these distal carpals. 



Owen says, in his "Fossil Keptilcs of the Liassic Forma- 

 tion,"* that: — 



"A carpus with one large and one small bone in a proxi- 

 mal row, and with a second large, and at least one small one 

 in a distal row, is another character b}' which the ptero- 

 sauria manifest their closer affinity to reptiles than to birds." 

 Now this is precisely the character of all those birds thus 

 far examined. 



EXPLANATION OF THE PLATES. 



Plate IV. THE TARSUS AND EMBRYOS. 



In every case the riglit leg and right wing are represeuted. For want 

 of room on the plates I have been compelled to leave out the humerus 

 and femur in most of the figures given. 



All the embryos are represeuted of natural size, and by referring to 

 them, an approximate idea may be formed of the size of the appendage 

 drawn, as well as the age and condition of the embrj'o. 



Reference to the embryo preceded by the initial E, follows explanation 

 of the figure, thus : Fig. 1, Spisella socialis. E. 18. 



Fig. 1. Spizella socialis. E. 18. 



The three bones separate, the fihulare being at the end of the filnda. 

 The 2d, 3d and 4th metatarsals not complete, while the 1st metatarsal 

 appears only as a few granules. 



Fig. 2. SjnzeUa socialis. E. 19. 



Tarsal joint appearing, in separation of cartilage between proximal 

 and distal tarsal bones. 



Fig. 3. Tardus fascescens. E. 21. 



The tarsals separate. The distal end of tibia widening so as to in- 

 clude the proximal tarsals. 



* PalKontogi-aphical Soc, Vol. XXIII, 1SG9. 



