Dr. E. Crisp on the Anntomy of the Anatidae. 73 



the female, is nearly of the same kind ; and the nature of their food, 

 both animal and vegetable, is very similar. Of animal food the 

 oceanic and diving ducks obtain a greater variety, including univalve 

 and bivalve shells ; but some of the freshwater ducks (so called), as 

 the Shoveller {Anas clypeata), obtain a large quantity of these, as I 

 have verified in several instances by dissection. 



If we look to their internal organization, we have here likewise a 

 great general resemblance. The lungs, heart, gullet, gizzard, intes- 

 tines and their appendices — the pancreas, spleen, kidneys, and oil- 

 glands — have nearly all the same character. 



I have placed on the table the sterna of twenty-two difFereut spe- 

 cies of ducks, and likewise the tracheae of nearly all the species of our 

 British ducks ; and it will be seen that, with the exception of the 

 Common Scoter (^«a« nigra) and the Surf Scoter {A. perspicillatd), 

 the lower part of the air- tube is ftimished with a bony enlarge- 

 ment, more or less complete in the different species of oceanic ducks, 

 and affording in these a greater variation as to form : thus, m the 

 King Duck {A. spectabilis) and in the Eider (^A. mollissima) this 

 protuberance is without membranous divisions, as in the freshwater 

 ducks ; and the same may be said of the Velvet Scoter {A. fuse a) ; 

 but the enlargement in the air-tube of this bird is seated some distance 

 above the bronchi. 



In Yarrell's * British Birds,' vol. iii. pp. 148, 202, descriptions 

 are given of the freshwater and oceanic ducks. The characteristics 

 of the former are said to be length of neck and wings, round tarsi, 

 unlobated and free hind toe. " In habits they may be stated gene- 

 rally as frequenting fresh water, but passing much of their time on 

 land, feeding in ditches and about the shallow margins of pools, ou 

 aquatic plants, insects, worms, and occasionally on small fish, taking 

 their food at or near the surface, possessing great powers of flight, 

 but seldom diving unless pursued. Of their internal parts, the 

 stomach is in the greatest degree muscular, forming a true gizzard ; 

 the intestines long ; the csecal appendages from 6 to 9 inches in 

 length in the larger birds, and decreasing only in proportion to the 

 size of the species. Of the bones it may be observed that the ribs 

 are short, the angle formed by the union of the first pair on each 

 side extending but little beyond the line of the posterior edge of the 

 sternum ; the keel of the breast-bone is deep, affording great extent 

 of surface for the attachment of large and powerful pectoral muscles ; 

 the enlargement at the bottom of the trachea in all of them is of 

 bone only. The males of this species are further remarkable for 

 becoming for a time during summer more or less Uke the females," 

 &c. 



At page 202, in speaking of the oceanic ducks, their food is said 

 to be " fish, shelled mollusca, Crustacea, and marine insects, but httle 

 or no vegetable production. Their powers of flight moderate, and 

 their walk embarrassed, from the backward position of their l^s. 

 Of their soft parts, the oesophagus is capable of great dilation ; the 

 stomach is a muscular gizzard, but the internal cavity is large, and 

 the sides comparatively thin. The ribs are elongated, and the keel 



