490 STRUCTUEE AND CLASSIFICATION OF BIRDS 



The glutai I.-V. are well developed. A very interesting 

 feature of the thigh muscles (referred to by Gareod ^) is the 

 existence of a small ' suprasciatic ' slip of muscle arising 

 behind the acetabulum, which reinforces the accessory 

 femorocaudal. The interest of this small muscle lies in the 

 fact that it has its precise counterpart in the struthious birds 

 {q.v.) This muscle was found by Forbes to be absent in a 

 male Crypturus tataupa ; it was present 

 in a female of the same species. 



The two deep flexor tendons fuse and 

 then supply digits II.-IV. ; before uniting 

 the flexor hallucis gives off a slender slip 

 to hallux, which is wanting in Crypturus 

 imdulatus. 



The skull of the tinamous, as was 

 first pointed out by Parker,^ is com- 

 pletely ' struthious ' so far as concerns the 

 palate. As will be seen from the annexed 

 cut (fig. 233) the vomer is broad and unites 

 in front with the maxillo-palatines, as in 

 Dromceus. Its ends receive behind the 

 pterygoid and palatines, which are thus 

 prevented from articulation with the 

 basisphenoidal rostrum. There are large 

 basipterygoid processes and the head of 

 the quadrate is single, as in struthious 

 birds. The supraorbital chain of bones 

 figured by Parker in Tinamus robustus 

 is another archaic skull character of these 

 birds. ^ The nasals, lacrymals, and 

 adjoining bones are very much like those of Bhea and not at 

 all like those of gallinaceous birds. Between the nasals 

 posteriorly is a considerable tract of ethmoid,^ appearing 



• ' On certain Muscles of the Thigh of Birds,' &c., P. Z. S. 1873, p. 642. 



' ' On the Osteology of Gallinaceous Birds and Tinamous,' Zool. Trans, v. 



■■' Absent, according to Lucas (' Notes on the Osteology of the Spotted 

 Tinamou,' Fr'oc. TJ. S. Nat.'Mus. s.. 1887, p. 157), in Nbthzira maculosa. 



' Erof. Pabkee wrote, in 1862 (loc. cit. p. 213) ; ' I suppose that in the tina- 

 mou, as in. other ostriches, the broad top of the ethmoid is separately developed 



Fig. 233.— Skuli. of 

 Tinamus robustus 

 (AriER Huxley). 



Pmx, premaxillse ; Mxp, 

 maxillo-palatines ; yo, 

 vomer ; H, palatines ; 

 Ptt pterygoids. 



