ANATOMICAL STRUCTURE OF ANTHROPOID APES. 189 



in the gorilla. In that animal, and in the orang, 

 a lower projection is displayed, extending behind 

 the sterno-mastoid as far as the shoulder, and 

 another extending to the^ pectoralis major muscle. 

 In the chimpanzee only the posterior segment is 

 developed. It has been asserted that in several 

 cases there is found a single, irregular laryngeal 

 sac, communicating with the two Morgagni sacs, 

 but I agree with Ehlers in thinking this impro- 

 bable. In such instances it seems likely that, owing 

 to the great want of symmetry in this organ, one 

 of the sacs has been overlooked. In an aged orang 

 the throat-pouches, fastened together by connective 

 tissue, and covered by the external skin of the 

 throat, hang down slackly and heavily over the 

 middle of the breast (see Fig. 9). According to 

 Sandifort, the siamang is the only one of the gibbons 

 which displays a single throat-pouch ; while Broca 

 asserts that it has two detached sacs, placed close 

 to the larynx.* The halves of the thyroid carti- 

 lage are generally connected with each other by an 

 intermediate piece. 



The trachea of anthropoids generally includes from 

 sixteen to eighteen cartilaginous rings, but in the 

 siamang there are twenty-one. They ramify into 

 branches which are, as a rule, wider on the right than 

 on the left side.f There is a further lateral ramifi- 



* Ortleetlcundige Beschryving van een volvassen Orang Oetan. 

 Verhandelingen over de natuurUjke geschiedenis der Neederlandsche 

 Bezittingen : Leiden, 1840. Bulletin de la SociitS d'Anthropologie 

 de Paris, ir. pp. 368-371 : 1869. 



t Comp. Aeby, Der Bronchialbaum der Sdugethiere tmd des 

 Menschen, p. 7, table v. fig. 11 : Leipzig, 1880. 



