1886.] POINTS IN THE ANATOMY OF CAPRIMTJLGID^. 151 



The intrinsic muscles of the syrinx are inserted on to the fifteenth 

 or sixteenth bronchial ring, much lower down therefore than in 

 Batrachostomus ; the first two bronchial rings are complete ; the 

 following fourteen are semirings, but are wide, firmly united to each 

 other, and ossified ; the membrana tympaniformis forms the inner 

 wall of this and of the following section of the bronchus. The 

 posterior section of each bronchus, as in Batrachostomus, is formed 

 of slender cartilaginous semirings separated by wide membranous 

 intervals. 



As far as the structure of the syrinx is concerned Steaiornis stands 

 alone ; Podaryus and Batrachostomus are closely similar to each 

 other, and are transitional between such genera as Caprhnulgus and 

 Steatornis ; the insertion of the intrinsic muscles so far down the 

 bronchus, and the similarity between the anterior rings of the bron- 

 chus and those of the trachea, is evidently an approach in structure 

 to the bronchial syrinx of Steatornis. ^gotheles resembles Batra- 

 chostomus more closely than it does Caprimulgus, but the number 

 of bronchial semirings which intervene between the trachea and the 

 insertion of the syringeal muscles is still further reduced. Capri- 

 mulgus, Chordeiles, and Nyctidromus are very closely allied in the 

 structure of their syrinx, which is tracheo-bronchial, and shows no 

 approach to the bronchial syrinx of Steatornis, as do the syringes of 

 Podargus, Batrachostomus, and (to a very much less extent) ^go- 

 theles. 



The arrangement of the genera of Caprimulgidse, as indicated 

 above by the structure of their syrinx, is, I believe, in accord with 

 the opinion of most ornithologists. With regard to other structural 

 characters, the following notes upon certain of the viscera and muscles 

 appear to be worth recording. 



Visceral Anatomy. 



The intestines of the Caprimulgidse are furnished with cseca, with 

 the exception of those of JSgotheles. Mr. Forbes has left a MS. 

 note to this effect, and 1 cannot find any trace of cBRca in the spirit- 

 preserved specimen of the last-mentioned form. In all the genera 

 the left lobe of the liver is rather the smaller, and a gall-bladder is 

 present save in Chordeiles^ . 



The air-sacs in one specimen of Steatornis were rather peculiar 

 in structure. The pcints in which they were found to diff'er from 

 other birds are in the posterior intermediate air-sac. This sac 

 on both sides of the body is considerably larger than the preceding 

 anterior intermediate sac, and is furnished with two principal ostia 

 placed near to the external border of the lung. These r pertures have 

 a diflPerent position in relation to each other on either side of the 

 body ; in the right lung these apertures do not both open into the 

 posterior intermediate air-sac as they do on the left side of the body ; 

 the most anterior of the two ostia opens into a small wedge-shaped air- 

 cell, which is completely separated by septa both from Ihe posterior 



1 Garrod MS. 



