OCR Text |
Show 1873.] CAROTID ARTERIES OF BIRDS. 459 pneumogastric nerve and jugular vein. Birds with this arrangement may be termed aves bicarotidince abnormales (see fig. 3.) Fig. 3. Fig. 4. Fig. 3. Carotids at the base of the neck in aves bicarotidince abnormales. Fig. 4. Carotids at the base of the neck in aves conjuncto-carotidince. Fourthly, the two carotids, running apparently as usual, directly they meet, join and continue as a single trunk till near the head, where the single vessel bifurcates, as in birds with a left carotid only. These Fig. 6. r.a h h Fig. 5. Carotids at the base of the neck in the genus Phoenicopterus, as found by myself in all specimens. Fig. 6. Carotids at the base of the neck in Cacatua sulphurea, according to Meckel. may be termed aves conjuncto-carotidince. In the common Bittern, where this condition obtains, the arteries (fig. 4) are equal in size or very nearly so ; but in the Flamingo (fig. 5) the left is extremely small, and has been on this account overlooked by previous observers, |