194 STRUCTURE AND CLASSIFICATION OF BIRDS 



parts of the spinal tract Xantholcema is more toucan-like 

 than any barbet. 



In Capita and Trachyplwnus NITZSCH has figured an 

 anterior bifurcation of the posterior part of the spinal tract, 

 much more marked in the former genus, where, indeed, I am 

 inclined to suspect a more detailed resemblance to XantJw- 

 la-ma than is suggested by NITZSCH'S figure. If this is not 

 the case, the New-World genus will be distinguished from 

 the Old- World genera by a double posterior spinal tract 

 divided by a break from the forked anterior tract. 



The tensor espatagii consist of a slighter tensor longus and 

 a wider brevis ; the tendons of both are simple, and each is 

 reinforced by a tendinous slip from the pectoralis. The 

 brevis tendon is simple, and terminates, as in the last two 

 families, upon the tendon of the extensor metacarpi radialis. 



In Capita, at any rate, there is a cucullaris propatagialis. 



FURBEINGEE had indicated a point of difference among the 

 barbets which concerns the rhomboideus profundiis. This 

 muscle in Meiglyptes (Picidse) and Ehamphastos is a large 

 fan-shaped muscle, arising from the tip of the ilium, as 

 well as from the spinous processes of certain of the dorsal 

 vertebrae, and is inserted from the tip to about halfway down 

 the scapula. In Capita this muscle is plainly divided into 

 t w o an anterior and a posterior of which the latter arises 

 from a few vertebrae and from tip of ilium. In Megalcema 

 the anterior section of this muscle is itself again divided 

 into two quite distinct parts. This family, like the wood- 

 peckers, toucans, and Passeres, has a latissimus dorso- 

 cutaneus, but no metapatagialis. 



The deltoid extends some way down the arm, as in other 

 allied birds and in Passeres ; it has no special scapular slip. 

 The barbets, like the woodpeckers and toucans, possess a 

 sesamoid ossicle, called the ' scapula accessoria,' which is 

 developed in the scapulo-humeral ligament ; from it arise 

 some of the fibres of the deltoid. This bone, again, is also 

 found in Passeres and owls, and in a host of other birds. 1 The 



1 See FURBRIXGEK, p. 229. FORBES laid too much stress upon its classifica- 

 tovy value in the present case. 



