Dr. Bancroft on the Sea-Devil of Jamaica. 449 



in regarding as attributes of the male gender among the Rays proper. * 

 The mouth was not placed as in the true Rays, but at the anterior extremity 

 of the body : each jaw represented a segment of a circle, but in the upper 

 jaw, as already explained, the arch was bent inwards towards the body, 

 whereas the lower jaw bore its arch outwards, from which conformation, 

 it projected about an inch before the upper jaw. In width the mouth 

 measured twenty-seven inches ; but the cavity which it opened into v?as 

 twice that width and three feet in depth, and from its vaulted form might 

 easily have contained a man. Another and singular deviation from the 

 ordinary structure of the mouth in the Ray family is, that neither along the 

 jaw, nor in any part of this vast cavity, was a single tooth discovered. The 

 tongue also was wanting. Immediately within and along the upper jaw 

 was a membranous fold or valve, twenty-one inches in length and nearly 

 two inches in breadth, which scarcely opened except at its extremities, 

 where the organs of smell are situated ; and beyond this was a second 

 valve, twenty-six inches long, and three to four inches broad, perfectly 

 pliant, serving apparently as a curtain to prevent the egress of any animals 

 that had entered the mouth, and thereby supplying in some measure the 

 want of teeth. This fish differs again from the Rays proper in the posi- 

 tion of its eyes, which are not, as in them, near each other on the dorsal 

 surface, but at the extreme edges of the head, and are placed about two 

 inches before the line of the jaws, and three feet and a half asunder. 

 They were inclosed in a strong cartilaginous oval case, admitting in some 

 degree of a rotatory motion, and measuring 3| inches to Sy^ths of an 

 inch, and placed horizontally. But the iris, which was also oval, black, 



* In a letter addressed to the Editor since the above communication was 

 written, Dr. Bancroft states that he has recently had an opportunity of ex- 

 amining a female of this species. " The principal external difference," he 

 remarks, " is, that the ventral fins, instead of consisting of one undivided 

 " lobe, have an appendix arising from it on the side next to the tail, which is 

 " fleshy, thick, firm, subcylindrical, compressed, and extending three or four 

 " inches beyond the ventral fins. This seems to constitute another deviation 

 " from the characters of the proper Rays, in which, according to Col. Montagu, 

 " it is the male alone that is furnished with a process from or near the inner 

 " side of the ventral fins, which he considers as a masculine appendage; while, 

 " in the Manta, it is the female, and not the male, that has such a process." 



Vol. IV. H H 



