DR. DAVY ON THE TORPEDO. 541 



two ; and others, as Linn^us and Block, with Willoughby, Ray, and Artedi, ad- 

 mitting only one*. 



That there are two distinct species in the Mediterranean, namely, the Occhiatella 

 and the Tremola, as the two kinds are vulgarly called at Rome, the spotted and non- 

 spotted of Bellon, there does not appear to me to be a doubt. But it appears more 

 than doubtful if any other true species exist in this sea. I draw this conclusion from 

 multiplied observations made both at Rome and in Malta. 



That these fish, the Occhiatella and Tremola, are distinct species, admits of satisfac- 

 tory proof. They differ not only in their colour and general appearance, but also some- 

 what in their form. The Occhiatella is more gracefully made than the Tremola ; its 

 fins are larger, especially its dorsal fins ; its water-valves are larger and different in 

 shape, and the openings behind the eyes to which they belong are guarded by much 

 smaller projections than protect those passages in the Tremola-f . And, internally, 

 there is a remarkable difference in the structure of the villous coat of the uterine 

 cavity : in the Occhiatella the villi are filamentous and detached, as represented in 

 Plate XXIV. fig. 4. ; in the Tremola they are continuous delicate plates or laminae, 

 as shown in Plate XXIV. fig. 3. J These characters are constant in all the different 

 specimens which I have examined. 



To these two well characterized species, it appears to me that all the varieties of 

 the Torpedo, at least those known hitherto in the Mediterranean, may be referred : 

 the T. unimaculata of Risso, and the second species of Rondelet§, to the Occhia- 

 tella ; and the varieties with dark irregular spots, or without spots, to the Tremola. 



CuviER, in the last edition of his Regne Animal, and Rudolphi, have so considered 

 the first-mentioned variety, the T. unimaculata, as it differs only in having one eye- 

 spot instead of five, the most common number. But it is not more uncommon to 

 meet with it having three or four spots than one ; and that this is purely accidental 



* Both those who have adopted four species and those who have allowed only one, appear to have followed 

 RoNDELET, in the latter instance critically, in the former literally, in proof of which the following passage may 

 be adduced. " Torpedinum genera quatuor faciraus, tria earum quae maculis notatae sunt, quartum ejus quae 

 maculis "aret. Quae genera omnia viribus et corporis specie non difFerunt, sed maculis tantum. Quare quae 

 de unius facultatibus et partium turn intemarum turn externarum descriptione dicuntur, eadem etiam reliquis 

 convenire existimato." (G. Rondeletii Libri de Piscibus, &c., p. 358. fol. Lugduni, 1554.) 



f Cuvier, in the edition of his R^gne Animal of 1830, (for an extract from which, as well as for one from 

 RuDOLPHi's Grundriss der Physiologic, relative to the Torpedo, I am indebted to my friend Dr. Allen Thom- 

 son,) distinguishes the Occhiatella by its spots, and by the absence " de dentelures charnues au bord de ses 

 Events." This does not hold good of any of the specimens which I have examined. The cartilaginous pro- 

 jections (which they really are) covered with cutis, I have found only smaller in the Occhiatella, not absent. 



X The villi increase in size during the period of pregnancy, and then contain a large quantity of blood. In 

 each filament, in the instance of the uterus of the Occhiatella, there is a blood-vessel reflected on itself, circu- 

 lating blood of a bright scarlet hue ; and in the lamellar structure of the uterus of the Tremola there is a si- 

 milar appearance of blood-vessels in loops. 



§ " Secunda Torpedinis species k prima difFert, qu6d maculas nigras, rotundas, circulis non distinctas ha- 

 beat, sed eadem pentagoni figurS, dispositas. Est etiam primae concolor." — Rondelet, p. 362. 

 MDCCCXXXIV. 4 A 



