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APPENDIX. 



FIG. 1. 



consideration, which results from the comparison of Cancroma with Eurypyga, and which presents, 

 perhaps, the most extreme modification in the form of the bill in two birds of the same family. 



As far as I was able to examine the viscera of the Baloeniceps, I could discover nothing that 

 would lead me to doubt its Ardeine affinities ; the stomach, liver, intestines, &c., of the two birds 

 appeared exactly to correspond in structure and arrangement. 



Directing my attention to the skin of Balceniceps, I was surprised at finding on the lower 

 part of the back, reaching from the end of the scapulars to the base of the tail, two large, well- 

 defined powder-down patches. The drawing 

 (fig. 1) represents these two patches in situ on 

 the body of the bird stripped of its feathers. 

 These remarkable patches are dark-coloured on 

 the inside of the skin, and on the outside the 

 down is of extreme thickness, and the quantity 

 of white or grey powder very great. This 

 powder, when examined under the microscope, 

 appears excessively oily, and will not mix with 

 water. It is greasy to the touch, and is evi- 

 dently produced by the growth of the down. 

 It appears, in fact, to be the quill-shafts of the 

 down broken up ; or perhaps the down roots 

 secrete this powder, which is distributed over 

 the entire plumage, rendering the feathers im- 

 pervious to water, in the same way that the oil- 

 glands effect this in other birds. In this bird, 

 however, the oil-glands are extremely small, not 

 larger than the oil-glands of a Sparrow. 



With reference to these patches, it is my intention to point out in the birds that I consider 

 allied to Balceniccps the existence of these patches of down ; and I may remark, that the attempt 

 to arrange animals by such means is not new ; as, for instance, in the case of the Ruminants, 

 some of the genera are distinguished by peculiar patches of hair, which are said to be glandular, 

 upon the legs, &c. ; and again the Vwerridae are distinguished by the existence or otherwise of 

 anal and other glands and pouches. 



I therefore proceed to point out the species more or less allied to Balceniceps that exhibit 

 these singular structures. In the New World form {Cancroma) this structure appears to be most 

 fully developed, this bird having four pairs of these powder-down patches, as shown in fig. 2, 

 which represents the upper, and fig. 3, which gives the lower surface of the body of this bird ; 

 while in the Old World form (Balceniceps) one pair only exist, as we have seen in fig. 1. 



It is worthy of notice, that the true Herons, which inhabit both the Old and New World, 

 and which have generally been regarded as the type of the group, have three pairs of these 

 patches ; the little and certainly aberrant form of Heron, Eurypyga, has only one pair of these 

 down patches ; while intermediate between this bird and the Herons come the Bitterns, in which 

 two pairs of these patches exist. 1 



1 Having had many opportunities of studying the habits of the living examples of Eurypyga and 

 Botaurus, I have observed a striking resemblance in these birds, particularly in the drooping and 



