130 



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, resembling young 

 beef. It is only found in shallows and inlets of the sea, and the 

 greatest number is said to be taken during the northerly monsoon, 

 near the mouth of the Johore river, in the inlet of the sea between 

 Singapore island and the main ; they seldom exceed eight or nine 

 feet in length, though they probably grow much larger, but are then 

 too strong to be caught. 



Observations on the Human Urethra, showing its internal Structure, as it 

 appeared in the Microscope ofF. Bauer, Esq. By Sir Everard Home, 

 Bart. V.P.R.S. Read June 1, 1820. [Phil. Trans. l8'2Q,p. 183.] 



Mr. Bauer has discovered, by the aid of the microscope, that the 

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

 an external muscular covering ; the former, very thin and destitute 

 of fibres, is thrown into folds in a collapsed state, and upon its sur- 

 face 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 observations show the fallacy of the 

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

 contractile fibres, and throw a new light upon the disease called 

 Stricture ; a spasmodic stricture being a contraction of a small por- 

 tion of the longitudinal muscular fibres, while the others are re- 

 laxed ; and a permanent stricture consisting in the exudation of co- 

 agulable lymph, in consequence of inflammation, between the fasciculi 

 of muscular fibres and upon the internal membrane. 



After adverting to what is known respecting the structure of the 

 corpus spongiosum, and corpora cavernosa, the author proceeds to 

 state the result of Mr. Bauer's examination of those parts. The cel- 

 lular structure of the corpora cavernosa is made up of many thin 

 membranous plates, very elastic, and so connected as to form a trel- 

 lis-work, the edge of which is attached to the elastic ligamentous 

 substance which surrounds them, and which forms the septum that 

 separates them. The structure of the corpus spongiosum resembles 

 that of the corpora cavernosa, except that the parts are formed upon 

 a smaller scale, and that there are no muscular fibres in its ligamentous 

 elastic covering. The various details and descriptions in this paper 

 are illustrated by Mr. Bauer's drawings. 



On the Errors in Longitude as determined by Chronometers at Sea, 

 arising from the Action of the Iron in the Ships upon the Chrono- 

 meters. By George Fisher, Esq. Communicated by John Barrow, 

 Esq. F.R.S. Read June 8, 1820. [Phil. Trans. 1820, p. 196.] 



The sudden alterations in the rates of chronometers, when taken 

 on board ships, are generally ascribed to the motion of the vessel ; but 



