MAMMALS. 589 



of tlie mouth by a fissure [glottis, rima cjlottidis). It is situated 

 between the inner margins of the Ugamenta thyreo-arytceno'idea ; 

 commonly there lie on each side two folds above each other; tlie 

 inferior (which include the so-named glottis vera) are named vocal 

 ligaments [chordae, vocales of Fekeein), In the true Cetacea these 

 inferior ligaments are absent. In most of the ruminants, on the 

 other hand, the superior are absent [Ugamenta thyreo-arytceno'idea 

 sujyeriora, Ugamenta glottidis spuria^). In the dolphins the aryta^- 

 noid cartilages in connexion with the epiglottis form a long pyra- 

 midal tube. In some cetaceans, a few ruminants, and many 

 species of monkeys, air-sacs are found in different situations, mostly 

 between the thyroid cartilage and the tongue-bone, which commu- 

 nicate with the larynx. On the thyroid cartilage is placed in 

 mammals a vascular organ, a gland without an efferent duct, the 

 thyreoid gland^. 



The kidneys in mammals are situated in the lumbar region near 

 the vertebrae, and on the outside of the sac of the peritoneum. In 

 many mammals the right kidney is placed higher than the left; 

 in man the reverse is observed nearly always. They are sur- 

 rounded by a loose areolar tissue, in which much fat is accumu- 

 lated; under this is the smooth proper membrane which covers the 

 tissue of the kidneys. In the mammals (distinguished in this 

 respect from all the other vertebrates,) that tissue presents itself in 

 two forms, a cortical and a medullary substance. The proper 

 secreting tissue of the kidneys consists of many tubules [tubuli 

 imniferi s. Belliniani), which pass from the papilla in the pelvis 

 of the kidney to its circumference. In the medullary substance 

 their course is straight, and they divide a few times successively 

 into two branches; afterwards their course in the cortical substance 

 is tortuous, vmtil they terminate in blind extremities near the 

 surface of the kidney. The numerous arteries, which in the corti- 

 cal substance divide pencil-wise into small clusters [glomeruli s. 

 corpora Malpighian a), forming many pendulous rings or loops, have 

 no immediate communication with these secretins; tubes, but are 



1 On the vocal organs of the mammals may be compared amongst others Casseeii 

 De vocis organis Historia anatomica, Ferrarice, 1601, folio ; L. Wolff Diss. anat. 

 {prces. B. A. Rudolphi) de Organis vocis Mammalium, Berolini, 18 12, 4to; J. F. 

 Brandt Ohservatlones anatomicce de Mammalium quormid., prcesertivi quadrumanorum, 

 vocis instramento, Berolini, 1826, 4to, and especially Willis On the mcchanisni of the 

 Larynx, Transact, of Cambridge Philos. Soc. 1832. 



