1874.] 263 [Brewer. 



Dr. T. M. Brewer remarked on some noticeable cases of 

 supposed Hybridism. 



Hybrids among the various forms of the duck tribe are by no 

 means of rare occurrence, and in several instances have been de- 

 scribed as new species. The specimens described by Audubon as 

 Anas breweri, the like of which has never since been obtained, is pre- 

 sumed to have been a cross between the wild Mallard and the Gad- 

 well, or grey duck (Chaulelasmus streperus). Several remarkable 

 cases of hybridism, where the evidences of the parentage on both 

 sides are well marked, have been recorded with great care. In a very 

 large proportion of these the common Mallard figures as one of the 

 parents. 



Somewhere about the year 1843, in company with my friend Prof. 

 Baird, I found a race of ducks of uncommon size in a farm-yard in 

 Carlisle, Pa. They were said to be, and their appearance tended to 

 confirm the statement, a cross between a male Canvass-back and a 

 female tame Mallard. The race was quite as productive as the pure, 

 unmixed Mallard, and existed at that time in several generations, 

 preserving with a remarkable degree of uniformity the marking of 

 their origin. Some of these were imported into Massachusetts ; but, 

 although at first they promised well, the breed is lost. Whether it is 

 still preserved at Carlisle, I do not know. 



A second instance is one more involved in doubt as to the reality 

 of its being a case of hybridism. Yet that it is one appears to be 

 a very general impression. Under the name of the Green-backed 

 Mallard, Anas maxima, Gosse described a wild duck shot near 

 Savanna-le-Mar, in the island of Jamaica. Mr. G. R. Gray, after 

 inspecting the specimen, pronounced it to be a hybrid. Against this 

 judgment, Mr. Gosse, however, contends. His reasons for regarding 

 it as a good species are, that it is a not uncommon kind in Jamaica, 

 and is one well known to the negro gunners, — that others precisely 

 similar have been known to occur in the neighboring waters, and that 

 this identical variety was known and described more than a hundred 

 years ago. Mr. Gosse quotes' from a MS., which states that a Mr. 

 Thistlewood shot, Nov. 19th, 1753, a duck identical with his speci- 

 men. The duck described by Gosse as Anas maxima weighed four 

 and one fourth pounds. Its head and neck is a velvety purple, 

 changeable to sea-green. The other colors are a rich chocolate with 



