276 STRL'OTURE AND CLASSIFICATION OF BIRDS 



the femorocaudal ; in Centropus and its allies, both in the 

 Old World and in the New, the accessory femorocaudal is 

 also present. In many groups of birds the arrangement of 

 the tendons ending in the patagium is very complicated. 

 This is not the case with the Cuculi, where the disposition of 

 these tendons is very uniform. For the most part the sim- 

 plicity is suggestive of the perhaps allied picarian birds. In 

 Cuculus canorus, for example, which has been figured by 

 ■G-AEROD, the tensor patagii brevis is inserted on to the fore 

 arm without any bifurcation. So too in Piaya, Saurothera. 

 The only exception to this which has been noted occurs in 

 Geococcyx, where the said tendon bifurcates just before its 

 insertion, the anterior branch being inserted on to the exten- 

 sor metacarpi radialis a little way in front of the main 

 attachment. This is also the case with Guira and Phmnico- 

 phaes. 



No cuckoo has any biceps slip. In some genera, e.g. in 

 Saurothera, Goccyzus, Pyrrhocentor, there is an attachment 

 between the . anconaeus and the humerus. In Guira there 

 is none. The expansor secundariorum is what Gaeeod 

 (see p. 85) has termed ' ciconiiform. The gluteus primus 

 is extensive in most cuckoos ; ' its origin in them reaches 

 behind the head of the humerus as well as in front. There 

 is no glutseus V. The deep plantar tendons of Pyrrhocentor 

 and Centropus are peculiar in that no branch is sent to 

 the hallux. 



The syrinx in the cuckoos shows greater variability than 

 in any other group of birds excepting the goatsuckers. We 

 meet with the typical tracheo-bronchial syrinx in a consider- 

 able number of genera, while in others is the much-modified 

 bronchial syrinx. The latter was first described many years 

 ago in Crotophaga by Johannes Muller. In that genus 

 the syrinx closely resembles that of Steatornis, which has 

 been already described in the introductory chapter (see p. 69). 

 There are, however, as might be imagined, differences- of 

 detail. In Crotophaga the membrana tympaniformis com- 

 mences at the seventh ring of the bronchi, the rings in front 

 ' Apparently absent or very slight in CiUiuluit. 



