278 Papers from the Marine Biological Laboratory at Tortugas. 



culty, seems to have no definite bony root, but to be connected with the 

 tough, leathery skin of the tail by a single growth. The spine of A . narinari, 

 which is easily torn from the tail, has a bifurcated root in all the Beaufort 

 and Key West specimens examined by me. In confirmation of this point 

 see page 276 for description of the spines of this ray preserved by Dr. 

 Coker in 1901. One has a double root, while the other has had the lower 

 end cut off. The only other figure of such a spine is that of Myliohatis 

 punctatus, figured but not described by Maclay and Macleay (1886). This 

 is reproduced here in figure 21, plate viii. It is bifurcated also, but less 

 markedly so than that of A. narinari, B in text-figure 5. 



The single dorsal fin is situated on the root of the tail just before the 

 spines. The tail under it is triangular in cross-section, the dorsal being 

 situated on the base of the triangle. In the photograph of the 4-spined 

 tail from Beaufort the anterior part of the fin has been cut off, but the 

 posterior portion shows a marking of which I have nowhere found mention 

 and which, being found in every specimen save one (and it in a bad state 

 oi preservation) which I have critically examined, seems to be quite constant. 

 This is the white splotch placed more or less vertically on the hinder edge 

 of the dorsal, but having around it always a dark margin.^ In small 

 specimens this splotch covers the greater portion of the fin, but in old and 

 large fish it is mainly in the upper and hinder portion. Other markings, 

 which I have noted on the tails of all these rays examined carefully, are a 

 white spot (occasionally two) at the base of the dorsal fin, a long white 

 splotch or streak underneath the spines, and below this (on the side of the 

 tail) a long, pointed, dark streak. This is true of Key West rays and of Mr. 

 Coles's huge specimens taken in 1912 (see fig. 9, plate v). Klunzinger (1871) 

 notes that his Red Sea specimen had a tail which was black everywhere save 

 underneath the root, where it was white. 



Another curious marking which I have found on tails of both small and 

 large specimens from Beaufort and Key West, results from the presence of 

 irregular, discontinuous dark indentations running vertically on the sides 

 of the tail from mid-dorsal to mid-ventral line, thus giving the tail an 

 appearance which may perhaps be best described as segmented. These 

 indentations are, in some cases at least, opposite each other near the base 

 of the tail, but farther away are placed "staggered," i. e., one on the right 

 placed about half-way between two on the left, and at a considerable distance 

 from each other. At the base of the tail, near the spines, these indentations 

 may be as near as half an inch, but toward the tip the spaces inclosed may 

 be as much as 2 or 3 inches long. On all the Key West specimens these 

 markings are very clear. I find these markings also on the dried tails of 

 another Beaufort Myliobatid, Rhinoptera bonasus. 



But one record of this has come to light. Jordan and Evermann (1898) 

 in volume iii of their " Fishes of North and Middle America," speak of the tail 

 of a Panama ray, Myliobatis asperrimus, heretofore referred to, as "crossed 



I This spot is figured but not referred to in Dumeril's A. latiroslris, fig. 8, plate iv. 



