1820.] Royal Society. 53 



projecting from the extremity of the upper jaw. Tlie position of 

 the incisor teeth is occupied by the rough bristly surfaces of the 

 palate and jaws, which enable the animal to browse upon the 

 marine vegetables which constitute its food. There are 12 cylin- 

 drical molares with flat crowns. The aperture of the ear is 

 remarkably small. There are no dorsal or ventral fins, and the 

 place of the anterior extremities is supplied by fins incapable of 

 supporting the animal when out of water. There are two append- 

 ages opening into the stomach near the junction of the duode- 

 num. The intestines are long. The liver is divided into two 

 large lobes, and there is a smaller tongue-shaped lobe which 

 covers the gall-bladder. The kidneys are large, and the urinary 

 bladder apparently capable of considerable distension. The 

 testicles are situated a little below the kidneys. The urethra 

 opens in a small tubercle between the two lobes of the glans 

 penis. The thymus gland is large, black, and friable. The 

 lungs are not lobulated, and the ventricles of the heart are sepa- 

 rated at their points. The head is remarkable for the manner in 

 which the anterior part of the upper jaw bends downward, the 

 lower jaw being proportionally truncated. There are 52 verte- 

 brae. The ribs are 18 on each side. The sternum is bifurcated 

 at the point, and articulated to the cartilages of the upper ribs. 

 There is no pelvis or posterior extremities, but opposite the 

 eighth and tenth lumbar vertebrae are two narrow flat bones 

 lodged in the flesh, one on each side. The scapula is thick, and 

 the humerus, radius and ulna short and strong. 



The flesh of this animal is delicate and juicy, and somewhat 

 resembles veal or young beef. It is only found in the shallows 

 and inlets of the sea ; and the greatest number is said to be 

 taken during the northern monsoon, near the mouth of the Johore 

 river, in the inlet of the sea between the island of Singapore and 

 the main. They seldom exceed eight or ten feet in length, 

 though the author considered it probable that they grow much 

 larger. 



June 1. — A paper, by^Sir E. Home, was read, entitled, 

 " Microscopical Observations on the Human Urethra." 



For the chief observations in this paper, the author confessed 

 himself indebted to Mr. Bauer. From these it appears that the 

 human urethra is made up of two parts ; an internal membrane, 

 and an external muscular covering. The former is very thin, 

 and destitute of fibres. It is thrown into folds in the collapsed 

 state, and upon its surface are numerous orifices of glands. The 

 latter is made up of short interwoven fibres, forming fasciculi, 

 united by an elastic substance of the consistence of mucus. 

 These facts show, in the author's opinion, the fallacy of the com- 

 mon opinion, that the lining of the urethra consists of circular 

 contractile fibres, and thus throws a new light on stricture ; a 

 spasmodic stricture being caused by a contraction of a small 

 portion of the longitudinal muscular fibres, while the others are 



