22 ME. ^Y. p. PYCEAFT ON THE 



arching over the neural canal form but a narrow bar. The odontoid ligament is 

 Tinossified. The neural arches of the 2nd to ^th cervicals form, as in the Palconiformes 

 and some Caprimulgi, a broad quadrate plate having the postero-external angle 

 produced into more or less prominent hyperapophyses. From the 5th to the 9th 

 vertebrae, the arch is deeply notched posteriorly, and the neural spine is either wanting 

 or very feebly developed. From the 6th to the 9th the vertebrae bear prominent 

 catapophyses, which at the 10th give place to liyj)apophyses, which are continued 

 backwards to terminate with the 2nd or 3rd thoracic vertebra. 



The thoracic vertebrfe are all free save the last, which is fused with the syn sacrum. 

 The hypapojihyses, which vary in length and slenderness, never extend beyond the 3rd 

 vertebra. The neural spines {e. (/. Asio, Strix) interlock by means of a pair of spinous 

 processes, which projecting backwards from the postero-superior angle of the vertebra 

 embrace the antero-superior angle of that next behind. This interlocking is further 

 strengthened, in Asio for example, by long backwardly directed processes extending 

 from the hyperajiophyses of the 1st and 2nd thoracic vertebrae, and by similar processes 

 formed by the production forwards and backwards of the external angles of the transverse 

 processes of the 4th to 6th vertebrae. Conspicuous pneumatic apertures open beneath 

 the transverse processes of the thoracic vertebrae. 



The synsacrum includes from 13 to 14 vertebrae. Of these, two are thoracic, four may 

 be lumbar, three lumbo-sacral, two sacral, and three caudal. 



The parapophyseal processes of the lumbar vertebrae are short, the last abutting 

 against the inferior border of the preacetabular ilium near its middle. 



A. planum coccygeum is generally present, and is esj)ecially distinct in certain forms, 

 e. g. Syrnimn, where it is isolated by a deep fovea pudendalis ; whilst in Buho, for 

 example, its distinctness is masked by retention of the parapophyseal processes of the 1st 

 and 2nd caudal vertebrae. 



The transverse processes of the free caudal vertebrae appear to be relatively longest 

 in Asio and Strix. Free intercentra are present in the most proximal vertebrae ; 

 posteriorly these elements fuse with the centra, forming blunt hypapophyses. 



As in other groups of birds, there is evidence of a slow process of reduction in the 

 length of the vertebral column, apparently brought about both by excalation and 

 absorption of the vertebrae, the former method taking place in the presacral region, 

 the latter in the postsacral region. 



A secondary process of reduction, affecting the number of vertebrae in the different 

 series, has caused the actual reduction in the total number of the series to be generally 

 overlooked. The reduction in the numbers of the different series chiefly affects the thoracic 

 and cervical series, and is largely due (1) to the backward shifting of the sternum, and 

 (2) to the reduction of the sternal facet for the sternal segments of the ribs. The 

 backward shifting has resulted in the divorce of certain sternal segments of ribs from their 

 articulation with the sternum, and the consequent transference of the vertebra bearing 

 the rib to the cervico-thoracic series. The degeneration and final disappearance of the 

 sternal rib rapidly follows this divorce : later the vertebral segment of the rib likewise 

 becomes reduced, finally disappearing also. At least this appears to be generally the 



