542 DR. DAVY ON THE TORPEDO. 



is proved by the circumstance, that in a brood of several foetal fish, of which all but 

 one resembled the parent in having five spots, the exception had three. The Occhia- 

 tella has been seen even with seven eye-spots. 



The varieties of the Tremola are the T. marmorata of Risso and the T. Galvanii, 

 which RuDOLPHi, and, I believe, latterly Cuvier, has considered identical in species. 

 This appears to me to be proved by their general character being the same, their 

 water-valves, fins, and uterine structure ; and further, by the circumstance, that be- 

 tween the two varieties (the former marked with black spots or patches irregularly 

 distributed, the latter without spots,) there is a complete gradation or intermixture, 

 both the spotting and colouring varying infinitely, so that it is difficult to find two 

 fish exactly similar in either respect. How much this variation is owing to locality 

 and other circumstances, it is difficult to decide. As the spotted fish is most fre- 

 quently caught where the bottom is sandy, and the other variety where it is muddy, 

 light may be concerned in the difference, and the spots may be produced like freckles, 

 by the action of light : and in process of time they may become hereditary, the foe- 

 tuses generally, even of these varieties, resembling in appearance the parent fish. 



RuDOLPHi has given to the Occhiatella species the Italian name of T. ocellata ; 

 perhaps the Latin word oculata * may be preferable. The other species he designates 

 as the T. marmorata, for which might be substituted the term diverslcolor, being 

 applicable to all the varieties of it, and descriptive of its quality of variableness of 

 appearance. 



For the information of travellers who may visit Malta, and wish to investigate the 

 electricity of the Torpedo, I may mention that this fish (both the T. oculata and 

 diversicolor) is called by the Maltese Haddayla, derived from a verb in their lan- 

 guage signifying to benumb or paralyze, and consequently that it should be inquired 

 for by this name, not by that of Torpedo, which is generally unknown here. I may 

 add further, by way of caution, that the Torpedo in Malta is often difficult to be 

 procured, partly owing to its being little sought after for the table, being used as an 

 article of food only by the indigent, and partly, I believe, from the uncertainty and 

 irregularity of its coming into shallow water. However, by paying well the fisher- 

 men, it may be obtained at all seasons ; and the longest time to wait may be a fort- 

 night or three weeks. 



3. An account of some additional Experiments on the Electricity of the Torpedo. 



Mr. Faraday in the Third Series of his Experimental Researches on Electricity, 

 states that he has little or no doubt, were Harris's electrometer applied to the Tor- 

 pedo, the evolution of heat would be observed -(-. I have made very many experiments 



* Pliny, by Block and others, is supposed to have applied this term to the Torpedo. As in the only passage 

 in which I am aware he has used it (Hist. Nat., lib. xxxii. cap. ii. — the passage is little more than a list of fish,) 

 the word Torpedo is also employed, as if applied to a different fish, the justness of their supposition is doubtful. 



t Philosophical Transactions, 1833, p. 46. 



