BIEDS. 359 



number as in mammals; also the principal divisions of them are 

 the same. The facial nerve is feebly developed. The first branch 

 of the fifth pair has a distribution which deviates from that in 

 mammals and seems to indicate that, in part, it also corresponds to 

 the second branch of that pair; also it is sometimes thicker than 

 the second; the third branch gives off no lingual nerve (comp. 

 above, p. 228). The tenth pair, that of the nervus vagxis, seems 

 to take the place of the n. linguaUs ; a branch from that pair joins 

 the glossopharyngeus, whilst a distinct lingual branch from the 

 vagus is often present in addition \ 



The upper cervical ganglion of the great sympathetic nerve 

 lies close to the outlet, from the cranium, of the ninth and tenth 

 pairs. From this ganglion two branches proceed to the head, which 

 communicate with branches of the fifth, seventh and ninth pairs. 

 The cervical portion of the great sympathetic enters the canal of 

 the transverse processes between the first and second cervical 

 vertebrae and issues from it again at the penultimate cervical 

 vertebra, then runs over the brachial plexus and forms in the 

 thoracic cavity large ganglia which are mutually connected by two 

 nervous filaments or a double limiting cord. In the posterior part 

 of the abdominal cavity the limiting cord again becomes single, 

 and the nerves of the two sides approach each other more and more 

 towards the mid-plane^. 



The sense of feeling cannot be highly developed in birds, since 

 their body, with the exception of the beak, of the legs, and in 

 some of certain parts of the head or the neck, is entirely covered 

 with feathers. The anterior limbs are absolutely unable to serve 

 for tact since they are changed into wings, the posterior too, 

 besides their use in standing and progressing, serve only for seizing 



1 Compare on the cerebral nerves in birds Schlemm Observafiones neurologicw, 

 Berolini, 1834, 4to, pp. 17 — 20, and M. J. Thuet Disquisitiones anatomicce Psitta- 

 coriim, Turici, 1838, 4to, pp. 30 — 32. 



2 Compare besides E. H. Weber Anat. comp. nervi symjMthici, pp. 24 — 38, also 

 BiSCHOFF Comment, de Nervi accessorii WilUsii Anatomia et Physiologia, Darmstadii, 

 1832, 4to, pp. 4T, 42. In the mesentery of birds there is an unpaired nervous cord 

 which proceeds from the rectum, where it is thickest, to the duodenum along the con- 

 volutions of the intestinal canal. At the cloaca is placed an elongated, large terminal 

 ganglion ; at the lowest part of the small intestine this nerve has no ganglion. See 

 the interesting investigations of Eemak in his memoir, Ueber ein selbstdndiges Darm- 

 nervensysl.em, Berlin, 1847, folio. 



