VERTEBRATE ZOOLOGY. 481 



Besides these, on each side of the head are developed 



(1) A supraocular lamella (10, 11); and 



(2) A subocular lamella (12, 13). 



All these multiple pieces (not less than 13 in number) are 

 distinctly differentiated at the period of moulting, and finally 

 "fall apart like the pieces of a coat of mail," although when 

 in high season the corneous covering is apparently homo- 

 geneous. These parts are assumed at maturity and in the 

 breeding season, and their development is coincident with 

 the assumption of the colors of the nuptial season. The full 

 breeding dress is thus marked, according to M. Bureau, by 

 (1) hypertrophy, (2) corneous outgrowths, and (3) peculiar 

 coloration, and its loss is conversely manifested by (1) atro- 

 phy, (2) deciduous corneous elements, and (3) plainer colora- 

 tion. 



Although, as has been stated, the remarkable features thus 

 enumerated are new to science, it has been suggested that 

 they may have been observed by the inhabitants of the re- 

 gions in which they abound ; and the German name attribut- 

 ed to the species in one instance, by Brehm (Larventauscher), 

 may involve a reminiscence of the knowledge of such changes, 

 the name implying a "mask-changer." The common form 

 of the German name, however, is Larventaucher, which means 

 simply a "diver with a mask." It is probable that the lat- 

 ter is the proper form, as it is not likely that the common 

 people had observed as closely as the contrary supposition 

 implies. The coincidence is, nevertheless, noteworthy. 



The Genus Mesites. 



A striking illustration of the slight value and evanescent 

 nature of the differences observable in birds, and which have 

 been used to characterize even " subclasses " and " orders," 

 is exemplified by the genus Mesites a form peculiar to Mad- 

 agascar. This type was originally placed, provisionally at 

 least, by Is. Geoffroy St.-Hilaire, G. R. Gray (at first), and 

 Bonaparte, among or near the Gallinaceous or Columbine 

 forms; later, by G. R. Gray, Sundevall, and Hartlaub, among 

 the Passerines in or near the HJupetidce, or the Motacillidw ; 

 and, later still, by Bartlett, near the Eurypygidw. In other 

 words, it has been referred to four different " orders " of or- 

 nithologists, and yet these orders were based chiefly on ex- 



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