478 PHILOSOPHICAL TRANSACTIONS. [anNO 1773, 



anterior transverse cartilages, which, passing one above and the other below the spine, support the 

 diaphragm, and uniting towards their extremities, form on either side a kind of clavicle and scapula. 

 h, h. The outward margin of the great lateral fin. — i, i. Its inner margin, confining witli tlie 



electric organ. — k. The articulation of the great lateral fin with tlie scapula. — 1, The abdomen. 



m, m, m, The place of the posterior transverse cartilage, which is single, united with the spine, 

 and supports on each side the smaller lateral fins. — n, n, n, n. The 2 smaller lateral fins. — o. The 

 anus. — p. The fin of the tail. 



Fig. 2, A view of the upper surface of tlie female, — a, a. An exposure of the upper part of the 

 right electric organ. — b. The skin which covered tlie organ. — c. The eyes, prominent and looking 

 horizontally outwards, but capable of being occasionally withdrawn into their sockets. — d. Two 

 circular apertures communicating with the mouth, and fiirnished each with a membrane, which in 

 air, as well as in water, plays regularly backwards and forwards across the aperture in the oflSce of 

 inspiration, — e. The place of the right brancliia. — f. The two fins of the back. — g, g. The place of 

 the anterior transverse cartilages. 



Fig. 3, A view of the under surfece of the male, whose size, as here represented, is in general 

 smaller than that of the female. — a, a. Two appendices, distinguishing the male species. 



XL. ^nalomical Observations on the Torpedo. By John Hunter, F. R.S.* p. 48 1 . 



I was desired some time since, by Mr. Walsh, whose experiments at La 

 Rochelle had determined the effect of the torpedo to be electrical, to dissect 

 and examine the peculiar organs by which that animal prodtices so extraordinary 

 an effect. This I have done in several subjects furnished to me by that gentle- 

 man. I am now desired by him to lay before the society, the observations I have 

 made ; and for the better understanding of them, to present, on his part, a male 

 and female torpedo in spirits ; in the latter of which the electric organs are 

 exposed in different views and sections ; likewise a copper plate, which he took 

 care to have engraved, exhibiting those organs. 



Of the general structure and anatomy of the torpedo I say nothing, since the 

 animal does not differ very materially, excepting in its electric organs, as they 

 have been properly named by Mr, Walsh, from the rest of the rays, of which 

 family it is well known to be. I will only premise, that the torpedo, of which I 

 treat, is about 18 inches long, 12 broad, and, in its central ^or thickest part, 

 2 inches thick; which is nearly the size of the female specimen, now presented 

 to the society, as well as of that from which the plate was taken : but where 

 there is any difference in the organ arising from difference in size, notice will 

 be taken of it in this account. 



The electric organs of the torpedo are placed on each side of the cranium and 

 gills, reaching from thence to the semicircular cartilages of each great fin, and 

 extending longitudinally from the anterior extremity of the animal to the trans- 

 verse cartilage, which divides the thorax from the abdomen ; and within these 



* Though this paper has been reprinted in Mr. J. H.'s Observations on the Animal Economy; yet as 

 being so immediately connected with Mr, Walsh's Memoir, it was thought proper to retain it in these 

 Abridgments. 



