ON LEPTOSOMA DISCOLOR. 151 



Cuckoos, Parrots, or Toucans. In this spirit-preserved specimen it is P. Z. S. 188'0, 



easily demonstrable that the fourth digit cannot naturally be placed in a P' ' * 



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 the view here taken as to Leptosoma not being a true zygo- 



dactyle 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, besides 

 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, I. 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 f. Between this tract and the manclibular rami, 

 extending as far as the angle of the jaw, a narrow naked space is left ; 

 at this point the inferior tract becomes continuous 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 to about f 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 



* 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). 



t 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. 



