ON THE BURSA FABRICII IN BIRDS. 15 



Fig. 6. 



Cloaca and Bursa of young Ostrich (female), viewed from behind. Most of the 



posterior wall of the bursa has been removed. 



A. External sphincter muscle. B. Cut surface of bursa. C. Opening of cloaca into 

 bursa. D, D'. Pointer passing from bursa to exterior. E, E. Ureters. F. 

 Oviduct. G-. Clitoris. H, H'. Pores ; beneath them the smooth, non-glandular 

 part of the bursa. 



in Casuarius picticollis in fig. 7 (p. 16), the only remains of its existence 

 being seen in the few irregular circular folds on the mucous membrane 

 at A. At what age this change supervenes is not yet quite clear. The p. z. S. 1877, 

 specimen of C. beccarii that died in the Society's Gardens last year, appa- P- 3i6 - 

 rently an adult female, corresponded entirely in the disposition of these 

 parts with the specimen of C. uniappendiculatus above described, which 

 died shortly before, and was quite a young bird when received in 1874. On 

 the other hand, in C. picticollis the bursa was entirely atrophied. This 

 specimen, which also arrived in 1874, was then not quite adult ; so that 

 at the period of its death it must have been about three years old. 

 Whether Apteryx agrees in these points also with the other StrutJiiones 

 I am unable to say, as both the specimens I have dissected presented no 

 trace of a bursa. Probably therefore in this, too, when adult the bursa 

 disappears almost completely. I have mentioned above the singular 

 differences shown by Signer Alesi to exist in the structure of the lym- 

 phatic follicles of the bursa of RTiea as compared with other birds. 



