326 AVES. 



it bears a proportion of one-tenth, in some of The liver is of a lighter colour in Birds of 



the latter of one-twenty-ninth part of the entire flight than in the heavier Water-fowl. Each 



body. lobe has its hepatic artery and vena portee. 



The liver (m m, fg. 163,165) is situated The hepatic arteries are proportionally small, 



a little above the middle of the thoracic-abdo- but the portal veins are of great size, being 



minal cavity, with its convex surface towards formed not only by the veins of the intestinal 



the abdominal parietes, and its concavity turned canal, pancreas, and spleen, but also by the 



towards the subjacent viscera : the right lobe inferior emulgent and sacral veins. The blood, 



covers the duodenum, pancreas, and part of the which has circulated in the liver, is returned 



small intestines ; the left lobe covers the pro- to the inferior cava by two venae hepaticse. 



ventriculus and part of the gizzard; and the There are occasionally some smaller hepatic 



apex of the heart is received between the upper veins in addition to the two principal ones. 



ends of these principal lobes. The liver is, as The coats of the portal and hepatic veins ap- 



it were, moulded upon all these parts, and pre- pear to be equally attached to the substance 



sents corresponding depressions where it comes of the liver. 



in contact with them. The biliary secretion is carried out of the liver 

 It is generally divided into two nearly by two and sometimes three ducts ; one of these 

 equal lobes, which are often separated for terminates directly in the intestine, and is a <he- 

 a short extent, and connected together by a patic duct ' (n,n,fg. 165); the other enters the 

 narrow isthmus of the glandular substance, gall-bladder, and is a ' cyst-hepatic duct ' (o',Jig. 

 In some birds, however, as in the Pigeon, 165); the cystic bile is conveyed to the duo- 

 Cormorant, Swan, and Goose, there is a third, denum by a ' cystic duct ' (o,Jig 165). Where, 

 smaller lobe, situated at the back of the liver as in a few instances, the gall-bladder does not 

 between the lateral lobes, which from its situ- exist, both hepatic ducts terminate separately 

 ation appears analogous to the lobulus Spigelii in the duodenum (w, w, Jig. 163); but in no 

 of Mammalia. In the Common Fowl the left case is there a single ductus communis cho- 

 lobe is occasionally cleft so deeply as to form ledochus as in Mammalia. 

 two lobes on that side. In some species the The gall-bladder (p, Jig. 165) is situated 

 right lobe exceeds the left in size ; ; this is most near the mesial edge of the concave or under 

 remarkable in the Bustard, in which the right side of the right lobe, and is commonly lodged 

 lobe extends into the pelvis. In the Eagle, in a shallow depression of the liver; but some- 

 however, the left lobe has been observed to be times, as in the Eagle, Bustard, and Cormorant, 

 the largest. Each lobe is invested by a double only a very small part of the bag is attached to the 

 membranous tunic, one embracing it closely, liver. It has the same structure as in Mamma- 

 the other surrounding it loosely, like the peri- lia, manifesting no visible muscular tunic, and 

 cardium of the heart. They are formed by having its inner surface delicately reticulated, 

 laminae of the peritoneum, which seems to The gall-bladder is present in all the Rap- 

 split at the exterior thin edge of the liver into tores, Insessores, and Natatores. It is want- 

 four layers, two being continued upon the ing in a great proportion of the Scansores, as 

 anterior and posterior surfaces adhering to them, in the Genus Rhamphastos and in the whole 

 the other two forming the loose exterior cap- of the Psittacida; and Cuculida. Among the 

 sule. Rasores the gall-bladder is constantly deficient 

 The principal ligament of the liver is formed in the Columbida or Dove-tribe alone, in which 

 by a large and strong duplicature of the peri- the creca are shorter than in any other vege- 

 toneum, which divides the abdomen longitu- table feeder: (n n, Jig. 163, are the two he- 

 dinally like the thoracic mediastinum in Mam- patic ducts terminating apart from one another 

 malia. It is reflected from the liriea alba and in the Pigeon.) The gall-bladder is occasion- 

 middle line of the sternum upon the pericar- ally absent, according to the French Acade- 

 dium, and passes deeply into the interspace of micians, in the Guinea-fowl; and they also 

 the lobes of the liver ; it is attached to these found it wanting in two out of six Demoi- 

 lobes through their whole extent, and connects selles ( Anthropoldes Virgo). The gall-blad- 

 thenrbelow to the gizzard on one side and to the der is small and sometimes absent in the 

 duodenal fold on the other: the lateral and Bittern: it is always wanting in the Ostrich, 

 posterior parts of the liver are attached to the The bile, as before observed, passes directly 

 contiguous air-cells; and the whole viscus is into the gall-bladder, and not by regurgitation 

 thus kept steady in its situation during the from a ductus choledochus ; the cyst-hepatic 

 rapid and violent movements of the bird. The duct arises from the right lobe, and is con- 

 ligament first described is analogous to the fal- tinned in some birds along that side of the 

 ciform ligament of Mammalia; and, although bag which is in contact with the liver, where it 

 there is no free margin inclosing a round liga- penetrates the coats of the cyst and terminates 

 ment, yet the remains of the umbilical vein about one-third from the lower or posterior end. 

 may be traced within the duplicature of the In the Horn-bill we found it passing over the 

 membranes forming the septum. As the mus- upper end of the bladder to the anterior or free 

 cular septum between the thorax and abdomen surface, and the cystic duct continued from 

 is wanting, there is consequently no coronary the point where the cyst-hepatic duct opened 

 ligament; but the numerous membranous pro- into the bladder; so that the cystic duct had 

 cesses which pass from the liver to the sur- a communicaton both with the reservoir and 

 rounding parts amply compensate for its ab- the cyst-hepatic duct; being somewhat ana- 

 sence. logous to the ductus communis choledochus; 



