1.898.] OSTEOLOGY OF BIRDS. 95 



b. All the dorsals free ; styloid processes short and blunt on all the cervical 

 ■vertebriE from the fifth backwards; 5th to 7th vertebra with a 

 slender bony bar from the metapophysis backwards to the hyper- 

 apophysis, neural crests present only on the second, third, and fourth. 

 Hypapophyses on the second and third cervicals, and from ninth cervical 

 backwards to the synsacral vertebrae, longest on the dorsals . . . Pha'ethon. 



B. Opisthoccelous dorsals, all of which are free. 



a. Hypapophyses present only on cervicals 1-3. All cervicals, save atlas 



and axis, bear styloid processes; meta- and hyperapophyses feebly 

 developed; haemal arches absent Fregata'. 



b. Hypapophyses present, on cervicals 1-1 very large, on 17-18 very feeble. 



Styloid processes from vertebra; 1-12; those of 8-10 long and slender. 

 Hsemal arches to vertebra; 8-12 ; distinct metapophyses from 4-1.", 

 from 7-11 large; no synsacral or dorsal hypapophyses Sula. 



c. Hypapophyses 1-3 and 1.3-23 very large, compressed. Synsacral hyp- 



apophyses 4, decreasing in size backwards ; hypapophyses 3-6 in the 

 form of a median ridge ; distinct styloid processes on all the vertebra 

 from 3-12, from 8-10 long, slender, those of the 9th extending as far 

 back as the posterior articular surface of the centrum ; no corajjlete 

 haemal arches ; neural crests from 2-7 distinct, in form of sharp ridges ; 

 hyperapophyses .3-10 very distinct : centrum elongated and compressed ; 

 16-18 cervicals much flattened ventrally Phalacrocorax. 



d. Hypapophyses of atlas and 15-lG large, those of the two latter much 



compressed ; those of the 2nd and 19-21 and 2.3rd in form of a low 

 median ridge, that of the 22nd with lateral expansions ventrad. 

 Synsacral hypapophyses 3, the 3rd vestigial. Anapophyses of 9-14 

 forming closed canals. Centra 3-13 grooved oentralli/. Styloid 

 processes 2-10 and 13-15 distinct, those of 8, 9, 10 long and slender, 

 8th extending as far back as the level of the posterior articular surface 

 of the centrum ; neural crests slightly developed ; anterior vertehrcs toith 

 much elongated cylindrical centra Plotus. 



C. SteENUM and PeCTOEAL GrIEDLE (figs. 1 & 2, pp. 87 & 88). 



A. The free end of the clavicle not provided with a facet for articulation 



with the acrocoracoid ; the furcular apophysis of the clavicle articulating 

 with the anterior border of the carina sterni, and not with its antero- 

 ventral angle. Carina stemi and region of corpus sterni bearing coracoid 

 grooves not produced far beyond the level of the costal process of the 

 sternum. Carina extending nearly the whole length of the corpus sterni, 

 the posterior border of which is doubly notched (=posterior lateral and 

 intermediate processes). Coracoids touching, with a suptracoracoid 

 foramen and large precoracoid process Pha'ethon. 



B. The free end of the clavicle with a facet for articulation with the acro- 



coracoid ; and the furcular apophysis of the clavicle articulating with 

 the antero-ventral angle of the carina sterni. Coracoids widely separate ; 

 no intermediate process to posterior border of the sternum. 



a. Greater part of carina sterni and region of sternum bearing the coracoid 



grooves produced far forward beyond the anterior lateral processes 

 of the sternum. Precoracoid well developed ; no supraeoracoid 

 foramen ^ula. 



b. Less than half the carina lying beyond the level of the anterior lateral 



process of the sternum, the inner angle of the outer border of which 

 is continuous with the outer angle of the coracoid groove. 

 a'. Furculum fused with carina sterni ; carina about three-foiu-ths the 

 length of the corpus sterni; precoracoid well developed; a supra- 

 eoracoid foramen Pdecanus. 



