84 



DR. E. CRISP ON THE ANATOMY OF 



[Feb. 26, 



bone only. Tbe males of tins species are further remarkable for 

 becoming for a time durina; summer more or less like 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 little 

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

 their walk embarrassed, from the backward position of their legs. 

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

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

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

 of the breast-bone decreases in depth in those species which in their 

 liabits most resemble the Merganser." 



In the above account there are several inaccuracies. Thus, the giz- 

 zard in many of the diving ducks, taking the weight of the bird into 

 consideration, is quite as muscular as in tbe freshwater ducks ; in- 

 deed the nature of their food requires this provision. I have not 

 found either the above-mentioned difference in the oesophagus or in 

 the length of the alimentary canal and appendices. The oceanic 

 ducks, moreover, take a large amount of vegetable food ; and the pro- 

 portional size of the pectoral muscles in many of them is quite as great 

 as in the freshwater ducks. The keel of the sternum, too, in some, is as 

 deep ; indeed the sterna of two of the ducks in question (the Summer 

 Duck and the Ferruginous) bear in every respect a great resemblance ; 

 but to bring this matter to a more practical bearing, let me take 

 eight ducks that I have recently dissected (four oceanic and four 

 freshwater), by way of comparison of the length of the intestinal 

 tubes. The appendices are included in the length of the canal. 



Name. 



Scaup {Anas marila) 



Golden-eye {A. clangula) 



Pochard {A.ferina) 



Common Scotrr {A. nigra) 



Shoveller {A. chipeata) 



Pintail {A. acuta) 



Wild Duck {A. boschas) 



Garganey Teal {A. querquedula) 



In twenty skeletons of different species of ducks that I have lately 

 examined, I find that all have fourteen cervical vertebrae, seven cau- 

 dal, and nine pairs of ribs, with the exception of the Summer Duck 

 (^Anas sponsa) and the Anas cceruleata : these have only eight ribs ; 

 but I scarcely need say that more than one specimen must be exa- 

 mined to ascertain whether this is the normal number. 



Time will not allow m.e to touch upon the minor differences, ex- 

 , ternal and internal, which apjjly more or less to all families of birds 

 Spe.aking generally, tlie short, thick-set, rounded form of the oceanic 



duck, its short 



and neck, shorter and flatter tarsi, lobated 



