460 CLASS XVI. 



tarsi, which in the Oscines have at the sides and behind a covering 

 which is simple and not divided into transverse scutes 1 . To this 

 there are only few exceptions, in which the posterior surface of the 

 tarsi is covered with transverse horny plates which in number 

 correspond with those on the anterior surface. In the Clamatores, 

 on the contrary, the tarsi are covered behind with small scales in 

 a network, or also with transverse horny plates, which in that case 

 are more numerous than the horny plates on the anterior surface. 

 SUNDEVALL had already given as a character, that the coverts of 

 the wings are short, and cover less than half the length of the 

 secondaiy quill-feathers 9 , a character however which is present in 

 the woodpeckers (see above p. 456).. Further he adds, that the first 

 quill-feather is shorter than the second, and often remains rudi- 

 mentary or is entirely wanting, so that there are only nine primary 

 quill-feathers 3 . Notwithstanding all these interesting characters, 

 still great difficulties are connected with the division of the Oscines 

 and Clamatores into two orders or even into two groups of the 

 same order. Cypselus and Hirundo, for instance, would then have 

 to be separated from each other, which are not merely analogous 

 forms like Glareola and Hirundo*. Nevertheless we shall as far 

 as possible have regard to these groups, and in the first place 

 notice the so-named Clamatores. 



Family XXVII. Opisthocomidce CABANIS (in part). Wing- 

 coverts large. Tarsi reticulate posteriorly. Claws compressed, 

 curved. Wings with ten primaries. Tail elongate, with ten 

 feathers. Bill short, convex, curved at the tip. Occiput crested. 



Colius BRISS., GM. Bill short, thick; upper mandible convex, 

 sub-vaulted, produced at the tip beyond the lower. Nostrils placed 

 in a pit at the base of bill. Orbital region naked. Tarsus covered 

 almost entirely with a single row of large scutes, with the posterior 

 margin alone reticulate. Hallux short, internal, versatile. Tail 



1 Archiv fur Natitrgesch. 1839, s. 332, u. f. f. ; H. BDEMEISTEE Einige Bemer- 

 kungen, u. s. w., ibid. 1840, s. 220 226; BLASIUS u. KEYSERLING Erwiederung, ibid. 

 s. 362 368; see also by these writers Die Wirbelihiere Europa's, I. 1840, 8vo. s. 80. 



2 Ornithologiskt System, Vetensk. Alcademiens Handlingar for 1835, pp. 43 130. 



3 Om Foglames Vingar, Vetensk. ATcad. Handl. 1843, pp. 303 384. Also the 

 normal number of secondary quill-feathers is nine, p. 377. Compare CABANIS Ornith. 

 Notizen, Arch.f. Naturgesch. 1847. s. 186 256, s. 303352. 



4 It is not, I trust, to be ascribed only to custom and to prejudice in favour of a 

 division generally adopted previously, if I cannot divest myself of this opinion. 



