18 CALIFOHNIA ACADEMY OF St'IKNUES 



Material is not al liaml lo (Iccidc tlio ri'latioii l)et\veen D. foiu/n and D. 

 Jipleiiiiti. The specimen lifted l)y -lordan (l.S!)") A, ]>. ;}.S9) from Afazatlan may bo 

 the latter, if the two species are distinct. In one of the Mazatian specimens, witli 

 the disk 32 cm. loiiji, the upper surface is naked, except three small spines on middle 

 line near .-honlder-<iirdle. The tail is al.so naked, and possesses, in addition to the 

 verv hi.iih ontaiieons fold helow, a free upper fin-fold half the heiiiht of the lower. 

 Tl is prol)al)]e that the two species are distincl. 



25. Pteroplatea crebripunctata (I'dcrs). 



Three specimens seen at Panama. 



The ]iroporti()ns of disk are not essentially diirfienl in /'. i-n'hr'ijiitiKiata, 

 I', rnvii, and /'. nnii-liirn. In all, the distance from tip of snout to front of anal slit 

 equals half the width of the disk (or a little li'ss than half in I\ rani); and the 

 extreme len<;lh of disk, from tip of snout to hinder mari;in of pectorals, is contaiiuMl 

 \l to IJ times in the width. A line joining angles of disk intersects very slightly 

 in advance of its middle a line from (ij) of snout to tip of tail. 



P . crebripunctata and P. maclura are extremely close, differing princii)ally in 

 color, the marblings and spots being finer in P. maclura, and the lighter markings 

 brighter in color, more sharply contrasting with the rest. P. rava has a sharper 

 snout than the others, the rostral angle being, however, in excess of a right angle 

 (110 degrees). The type of P. rava is a male specimen, 29 em. long, with well 

 developed claspers and no trace of caudal sj^ine. 



Family M VLIOJ'.ATID.E. 

 26. Aetobatus narinari (Euphrasen). 



Frequent]}' seen; three sj^ecinicns preserved, one of which has measurements 

 as given below. 



Rostro-frontal fontanel nai'rowing anteriorly to opposite the hinder margin of 

 eyes, then abruptly expanding; its greatest width anteriorly, 21 mm.; least width at the 

 constriction, 13 mm ; greatest width posteriorly, opposite middle of spiracles, 18 mm. 



mm. 



Tip of snout to front of anus 323 



Tip of snout to posterior margin of pectorals 365 



Width of disk 615 



Length of tail (broken) 1200 



Greatest breadth of head (at anterior origin of pectorals) 106 



Width at eyes (including the latter) 87 



Width of cranium opposite middle of eyes 53 



Width of snout opposite front of eyes 56 



Length of spiracle 31 



Tip of snout to middle of nasal flap 61 



Width of mouth 44 



Diameter of iris 1 1 



The Panama specimens agree entirely with those described by Jordan (1895 

 b, p. 391). The com2)arative measurements given in the paper cited are often 



