1880.] MR. W. A. FORBES ON LEPTOSOMA DISCOLOR. 467 



birds as the Cuckoos, Parrots, or Toucans. In this spirit-preserved 

 specimen it is easily demonstrable that the fourth digit cannot 

 naturally be placed in a really reversed position, like that of the 

 above-named birds. While the second and third toes look directly 

 backwards, the hallux looks inwards and forwards, and the fourth 

 toe inwards and slightly backwards at its apex, there being, as it 

 were, a slight twist in its axis'. However much the fourth toe is 

 bent backwards (and this is only done by the exercise of some little 

 force), its plantar surface always looks more or less inwards. The 

 presently-to-be-described arrangement of the deep plantar tendons 

 also confirms tlie view here taken as to Leptosoma not being a true 

 zygodactyle bird. 



Pterylosis. — As regards Leptosoma, Nitzsch only noted the presence 

 of an aftershaft and 12 rectrices, he only having been able to examine 

 a stuffed specimen. Mr. Sclater, in his above-mentioned paper, be- 

 sides describing the two characteristic lumbar powder-down patches 

 of this bird, briefly alludes to the pterylosis, which " appears nearly 

 similar to that assigned by Nitzsch to Coracias and Eurystomus." 

 These features are diagrammatically represented in a woodcut 

 (fig. 5, /. c). 



The following is a more detailed description : — 



The inferior tract divides about 1 inch behind the junction of the 

 rami of mandible — the (badly) so-called "chin-angle" — from which 

 it starts as a narrow, single tract'. Between this tract and the 

 mandibular rami, extending as far as the angle of the jaw, a narrow 

 naked space is left ; at this point the inferior tract becomes continu- 

 ous with the feathering of the head above, so that here the neck, 

 except for the narrow median ventral apterium, is continuously 

 feathered. This continuous feathering extends downwards till about 

 I inch above the shoulder, when, the inferior and dorsal tracts 

 diverging, the lateral neck-space is formed. The inferior tracts 

 diverge gradually as they approach the breast, and then run parallel 

 to each other over the pectoral muscles and abdomen to the sides of 

 the vent, leaving a rather wide bare carinal space, with a few scattered 

 down-feathers. As the inferior tract emerges on the breast, it gives 

 off a branch to the anterior margin of the patagium ; and this at first 

 is dilated somewhat, so that the space between it and the main tract 

 is feathered. The broad humeral tract is also connected with the 

 inferior tract where the latter gives off this patagial branch. In the 

 lower part of the neck the inferior tract is about 8 feathers broad, on 

 the breast about 6, and on the abdomen only 2. About the middle 

 of the sternum the outer pectoral tract, which is about 4 feathers 

 wide and slightly stronger than the main tract, is given off; it is 



' This disposition of the fourth toe makes Leptosoma, at first sight, look as if 

 it had three toes anteriorly directed, and no doubt accounts for Mr. Sharpe 

 entirely omitting any notice of its peculiar feet in his paper on the Coraciidae 

 [of. Ibis, 1871, pp. 187, 285). 



^ In Coracias garrula the naked median space left between the halves of the 

 inferior tract extends quite up to the symphysis, so that the inferior tract is 

 double from the commencement. 



Proc. Zool. Soc— 1880, No. XXXI. 31 



