2l8 



GENERAL ORNITHOLOGY 



not meeting each other. They are wanting in Struthio, Rhea, 

 Apteryx, and some Psiitacidce. Besides curving toward each other, 



the clavicles have usually a 

 fore-and-aft curvature, con- 

 vex forward. In general, 

 the strength of the clavicles, 

 msimi id- \ mm< # the firmness of their connec- 



fmmSI \mm'^ / tions, and the openness of the 



V or U, are indications of 

 the volitorial or natatorial 

 power of the wings. The 

 end of the furculum is hol- 

 lowed for a fold of the wind- 

 pipe in the crested pintado. 



4. THE PELVIC ARCH 



The Pelvis (Lat. jjf/m, a 

 basin. Fig. 60) is that pos- 

 terior part of the trunk 

 which receives the urogeni- 

 tal, and lower portion of the 

 digestive, viscera. It consists 

 of the sacrarium on the 

 middle dorsal line, flanked 

 on each side by the bones of 

 the pelvic arch, which sup- 

 ports the hind limb. In ver- 

 tebrates generally the pelvic 

 basin is completed on the 

 ventral aspect by union {sym- 

 lihysis; Gr. o-vv, sun, together; 

 <^i,'o-is, growth) of the bones 

 from opposite sides. Except- 

 ing only Struthio, which has 

 a pubic symphysis ; and Bhea, 



Fig. CO.— Pelvis of a heron (Ardm hcrodias), nat. which haS an ischiaC SVni- 



size, viewed from below ; from nature by Dr. R. W. i • • . i i , i ^ 



Shufelflt, U.S.A. dl, dorsolumbar vertebra; to and phySlS JUSt DelOW the Sacral 



including the last one, sc ; below sc, for the extent of -.rovfoVi-rco fVio i^QlTn'c, r^f 



the Zfirg-e black spaces (opposite the arrow) are the veiLeuice, Lllb peiVlS OI a 



true sacral vertebra -us urosacral vertebrii? (op- -bird is entirely OPCU beloW 



posite the hve oval black spaces; II, ilium; Is, i i i • i i 



ischium ; P, pubis ; o&, obturator foramen. The and behind ; each pelvic 



arrow flies into the acetabulum. ^ ^ ^ • r- i • , i 



arch ankylosing firmly with 

 the sacral vertebrse to form a roof over the viscera above 

 named. This sacro- iliac ankylosis is commonly coextensive 

 with the confluence of the many vertebrjB Avhich make the 



