OCR Text |
Show 1899.] OSTEOLOGY OF THE TUBINARES. 407 b'. Posterior border of sternum with four deep notches; spina externa blunt or bifid Puffinus. Majaqueus. Bulweria. Prion. CEstrelata. Pagodroma. c'. Outer pair of notches obliterated or feebly developed (sometimes forming fenestras) Priocella. Thalassa'ca. Fulnuirus. Priofinus. d'. Posterior border of sternum with 4 very slight notches; corpus sterni with pneumatic opening on anterior region of dorsal surface. Ossifraya. b. Coracoid grooves forming a right angle with the sternum ; base of coracoids not more than ^ the width of the long axis ; sternal ribs almost entirely confined to anterior latei'al process ; furculum without a distinct hypocleideum ; posterior border of corpus sterni entire... Pelecanoides. B. Pneumatic foramina of dorsal surface of sternum conspicuous, extending along the whole length of median line of the sternum ; carina merging into the sternal plate some distance in front of the metasternum ; posterior lateral processes projecting far beyond the level of the metasternum. Diomedeidce. D. PELVIC GIRDLE. Pi*e- longer than post-acetabular ilium ; ischium produced far backwards in the form of a long narrow bar of bone, its free end deflected and firmly bound to, or even fused with, the pubis, so that the obturator fissure is closed behind ; obturator foramen never completely shut off from the fissure. A. Pre-ilia not meeting in the mid-dorsal line above the neural crest of the synsacrum ; innominate free. a. Size small, total length of pelvis not exceeding 1*4 in.; postacetabular ilium with its dorsal border obliquely truncated and ill-defined; free ends of ischium and pubis fused. a'. Obturator fissure very narrow ; pre-ilia widely separated ; obturator foramen open posteriorly ; lumbar enlargement of synsacrum large and lying in front of the acetabular region. a". Pre-ilium not expanded distally Procellaria. b". Pre-ilium expanded distally Oceanodroma . b'. Obturator fissure very wide ; lumbar enlargement of synsacrum slight, lying in mid-acetabular region. c". Pre-ilia not rising beyond the level of the base of the synsacral neural crest; obturator foramen separated from the fissure by a broad bar of bone Pelayodroma. d". Pre-ilia rising to the level of the top of the neural crest, or nearly so. a3. Obturator foramen and fissure confluent. a4. Dorsal border of pre-ilium pressed closely to the lumbar enlargement, which is almost entirely preacetabular; greatest width of synsacrum about 3 its length Oceanites. bx. Dorsal border of pre-ilium separated by a deep groove from the lumbar enlargement; greatest width of synsacrum about | its length Cymodroma. b3. Obturator foramen separated from the fissure by a broad bar of bone; pre-ilia pointed in front Freyetta 27* |