186".] DR. E. CRISP ON THE HIPPOPOTAMUS. 609 



posterior edges flattened and measuring ^ inch in width. The an- 

 terior edges, which form the glottis, are thin ; and by their apposition 

 the glottideal sUt is entirely closed. The vocal ligaments are very 

 slightly developed. The state of the larynx and of the surrounding 

 parts prevented my making a careful inspection of the laryngeal 

 muscles, an investigation that will fully repay future inquirers. 



The trachea consists of twenty-three rings ; it is of moderate 

 calibre (1 inch), less capacious than in many young non-aquatic ani- 

 mals; its size is nearly uniform ; and, as in most quadrupeds, it has 

 three terminal branches, the two on the right side being nearer to- 

 gether than usual. 1 have placed the larynx and trachea of the 

 Porpoise and Dolphin on the table to show the resemblance of the 

 upper part of these tubes to that of the Hippopotamus. 



The heart is of a rounded form: it weighs 21 oz. ; its length 

 from the root of the aorta to the apex 6 inches, and its width at the 

 base the same. The external course of the coronary arteries is well 

 marked, their mouths large and in the usual situation. The pul- 

 monary artery of very large calibre. The aorta also of large size, 

 its coats one-third thicker than those of the last-named vessel. The 

 first large primitive branch (innominata) is 1|^ inch from the semi- 

 lunar valves, the second (subclavian), about one-half its calibre, close 

 to it. The coats of the first-named arterial branch are of unusual 

 thickness. The aortic and pulmonary semilunar valves present no- 

 thing worthy of notice, except that they have no corpora Arantii. 



The ventricles are nearly of equal size, the left being rather more 

 capacious. The sides of the right ventricle are generally smooth, 

 whilst those of the left are reticulated ; numerous cross bands are 

 present at the apex of this ventricle, all passing in the lateral di- 

 rection of the cavity. The parietes of the left ventricle measure 

 about 1 inch in thickness, whilst those of the right are only ^ inch. 

 The septum is very thick, measuring at its upper part 1| inch in 

 thickness. 



The tendons of the mitral valve, fifteen in number, arise from 

 two fleshy columns, the posterior being much larger than the ante- 

 rior, although less prominent. 



The tendons of the tricuspid valve, seventeen in number, spring 

 from three columns (so called), one prominent and nipple-like, the 

 others but little raised above the surface. 



The cavities of the auricles are of about the same capacity ; but 

 the appendix of the right auricle is larger, and its parietes thinner 

 and more distensible. In both appendices the musculi pectinati are 

 very numerous, those in the right forming a double reticulated layer 

 of bands, and presenting a very beautiful appearance. The foramen 

 ovale is deep and about the size of a shilling ; it is perfectly closed, 

 and a small nipple-like process projects from its centre. The pro- 

 jection at the upper part of the circle (isthmus Vieusseni) is well 

 marked. The Eustachian valve is but imperfectly developed ; indeed, 

 with the exception of a slight semicircular elevation, it can scarcely 

 be said to exist ; there is no tubercle of Lower so-called. The open- 

 ings of the two coronary veins are seen an inch below the foramen 



