318 NATATORES. 



eontrary directions ; so that by their rubbing against one another it is 

 against the grain in one direction, and with it in another 1 . 



They have two very long caeca, which become very small before they 

 enter the colon ; this is bnt short, has a large valve, and forms at the 

 bottom a pretty large cavity [cloaca 2 ]. The ductus hepaticus passes into 

 the body of the gall-bladder, and the ductus cysticus passes, without 

 any duct entering it, to the duodenum just after it has its first turn 3 . 

 The bile is of a dark transparent green, not very thick. The testicles 

 are very small 4 . The spleen has its veins running on the outside, like 

 the kidney of a lion. The two small glands on each side of the trachea, 

 when blown into, fill the veins with air : they are of a dark brown mixed 

 with blue. On their lower ends is placed a small body of an orange 

 colour, which seems to have no communication with the other, [judging] 

 by the air which was thrown into the other ; nor do they fill anything 

 but veins when blown into. There are two oblong lymphatic glands on 

 each side of the former ; when blown into, there is a lymphatic to be 

 observed passing from this lower end, and entering the subclavian vein. 



The Eustachian tube in a swan passes from the lower part of the 

 tympanum near the membrana tympani by an oval hole in the bone. 

 Besides that, there is another canal leading forward and inward like 

 the tube in the human ; but this is blind, and seems to communicate on 

 its inner edge with the cells of the lower part of the occiput. The bony 

 part of this canal opens on the basis of the skull a little way behind the 

 articulation of the bones of both jaws to the basis of the skull ; the two 

 [Eustachian] openings have a little thin plate of bone projecting over 

 them, so that they are not seen. From this they pass forwards for 

 about half an inch, in one common pipe, which becomes larger and 

 larger, and opens into the mouth or beginning of the fauces, just behind 

 the posterior nares : the membranous part of tbe tube is rugous. The 

 septum narium is irregular and very vascular ; and there is an opening 

 at the anterior part between the two nostrils, just where the two nostrils 

 open externally. The internal cavity of the nose is very irregular, the 

 turbinated cartilages forming many cavities ; and, besides these, there 

 are cavities answering to our sinuses. There is one on the outside of 

 the nose, behind the root of the beak, laterally above the angle of the 

 mouth, and below and before the eye : it is only covered by the common 

 integuments outwardly; on the internal surface it is very irregular, 

 and has a duct passing into the nose : at its posterior part it is lined by 

 a very vascular membrane, and the inner surface is no more than the 

 outer surface of the turbinated cartilages. There is another deeper 



1 [Hunt, Preps. Phys. Series, Nos. 530—532.] 2 |" Ib . Nos . 57^ 743.] 



2 [lb. No. 816.] 4 [lb. No. 2407.] 



