340 MR. W. K. PARKER ON THE OSTEOLOGY OF BALAINICEPS REX. 
formed by the furculum in front of the head of the coracoid, begins at the middle of the 
furcular ramus—in the Baleniceps at the upper third. In these two birds the enlarge- 
ment is sudden (being thick and oval in Baleniceps, and flat and wide in the Pelican) ; 
but in Cormorants, Gannets, Eagles, Hawks, Swifts, &c., the enlargement is very gradual. 
The sudden turn backwards which the ramus takes at the thick part is very peculiar in 
the Baleeniceps, a more perfect angle being formed there than in the Pelican and Gannet ; 
but it is still a very obtuse angle ; whilst in the Cormorant the thick articular third of 
each ramus is at a right angle with the lower contracted two-thirds. The middle con- 
tracted part of each furcular ramus is oval in section ; the enlarged inferior part is con- 
vex without and concave within, whilst above their junction there is a transverse fossa 
full of pneumatic holes. The furculum is a peculiarly ornithic bone, but its feeble de- 
velopment in the struthious birds explains its nature as the homologue of the human 
clavicle ; whilst Professor Owen considers it is also homologous with the large heemapo- 
physes of the atlas of Fishes’. 
The scapula in typical fish is composed of two pieces, and in them the coracoid attains 
its greatest dimensions. The former element (although composed of two pieces) is, in 
Professor Owen’s opinion, the pleurapophysis of the occipital vertebrz ; whilst the latter, 
the coracoid, is its hemapophysis. This scapulo-coracoid hemal arch, according to 
Professor Owen, always follows the heart and respiratory organs in the Vertebrata; so 
that the protection of these parts being in birds confined to such posterior vertebre, 
gives rise to this enormous displacement of these inferior elements of the occipital ver- 
tebra. In Fishes the pelvis often swings beneath the occipital hemal arch, and is as 
much displaced as the scapula, coracoid, and clavicle are in birds. In the latter class 
the pelvis is not displaced, the ilium being (in Owenian nomenclature) the extremely 
enlarged distal piece of a sacral pleurapophysis, whilst the ischium and pubis are 
heemapophysial in their nature ; one of the pairs of bones belonging to the ilium, whilst 
the other has its single-centred pleurapophysis® stunted and unconnected with its hema- 
pophysis. The terms epi-, hyo-, ento-, hypo- and xiphi-sternal processes are very con- 
venient ; but in his little work ‘The Skeleton and the Teeth,’ p. 215, Professor Owen 
says that Geoffroy St. Hilaire was wrong in supposing that these parts (with the excep- 
tion of the ento-sternal) are homologous with the epi-, hyo-, hypo- and xiphi-sternal 
bones of the Chelonia. The circle of bones which in this latter class articulate with the 
expanded pleurapophyses above, and with the epi-, hyo-, hypo and xiphi- sternals below, 
are mere dermal plates ; whilst the lateral pairs of the bones of the plastron are the 
* There are, however, very grave reasons for doubting whether the clavicle of birds belongs to the same ver- 
tebra ;—our opinion is that it does not. 
* Professor Owen’s views of the nature of limbs have not been corroborated by the researches of embryologists ; 
Mr. Huxley says that ‘the pectoral arch is originally totally distinct from the skull’ ; and Dr. Falconer has drawn 
my attention to Professor Goodsir’s view that the pectoral members belong to, and are developments from, several 
somatomes and meta-somatomes. (Goodsir, op. cit., p. 178; Huxley, op. cit., p. 53.) 
