432 



ZOOLOGY 



SECT. 



hu 



side (Fig. 1070, dg. ^) : this brings the total number of digits upto 



four, the fifth of the pentadactyle hand alone being unrepresented. 



The simplest type of pelvic girdle is found in Apteryx (Fig. 



1071) and the Tinamous, in which 

 botli pubis and ischium are free 

 along their whole length, as in 

 Dinosaurs. In the Emu and 

 Cassowary the pubis and ischium 

 unite by cartilage or bone at their 

 posterior end with the ilium, and 

 in most Biids the union between 

 the two last is extensive, the deep 

 ischiadic notch being replaced by a 

 small foramen. In the embryonic 

 condition (Fig. 1072) the ilium has 

 a very small pre-acetabular portion, 

 the pubis and ischium are nearly 

 vertical, and there is a distinct 

 pectineal process {pp) — retained in 

 Apteryx (Fig. 1071,^.) — the whole 

 pubis being singularly like that of 

 a Dinosaur, In the Ostrich alone 

 the pubes unite in the middle 

 ventral line to form a symphysis : Rhea presents the unique 

 peculiarity of a dorsal symphysis of the ischia, just below the 

 vertebral column: in the Emu the posterior end of the pubis 



Fig. ] 070.— Sterna wllsoni (Tern). 

 Fore-limb of embryo. d(j. 1 — U, digits 

 ku. humerus ; ra. radiUR ; v.t. ulna. 

 (After Leighton.) 



Firt. 1071.— Apteryx australis. Left innominate, a. acetabulum ; i(. ilium ; is. ischium; 

 p. pectineal process ; lA. pubis. (From Wiedersheim's Comparative Anatomy , after Marsh.) 



gives off a slender process, which extends forwards close to the 

 ventral edge of that bone and probably represents the epi-pubis 

 of Reptiles, 



