l4 dALIFOKNlA ACADEMY OF SCtENCES 



Family PRISTID^. 



14. Pristis zephyreus {Jordan & Starks). 



A saw, 80 cm. long, was procured fresh in the market. A young specimen 

 entire, 90 cm. in total length, was taken in fresh or slightly brackish water in a 

 tributary of the Rio Grande at Miraflores. The smaller specimen agrees well with 

 the type of the species. 



Some statements in the original description which might lead to confusion 

 are explained or corrected below. 



The teeth are all deeply grooved behind, the groove with sharply trenchant 

 edges. In both of the Panama specimens the teeth are in 22 pairs. The inter- 

 spaces between the hind teeth are 4 times the base of teeth in the young, 2i times 

 in the adult. The length of the front teeth is slightly more than I the breadth of 

 the saw between them in young, 2| in this width in adults. Distance between first 

 and second tooth 21 times base of first in young, twice base of first in adult. Width 

 of mouth slightly less than distance between tips of hinder teeth. The "slant 

 height of pectoral" of the original description includes the anterior margin of 

 the whole pectoral mass, from its angle forward to a point just behind eye. The 

 "lower lobe" of caudal is the distance from anterior insertion of lobe to tip of fin. 

 The saw in the type is 28 cm. long from base to tip, 31 cm. from tip of saw to front 

 of nostril. 



Family RHINOBATID^E. 



15. Rhinobatus leucorhynchus (Gunther). 



Seen on two occasions only. 



The relationship is extremely close between this species and JR. glaucostigma,' 

 which is abundant at Mazatlan. R. leucorhynchus has no slate-colored sjjots on the 

 back, and no black blotch on the under side of the snout. The rostral ridges are 

 much narrower, and the rostral cartilage tapers more anteriorly. The snout is 

 broadly triangular, with almost perfectly straight sides, which are slightly concave 

 near tip, making the latter narrow and sharp. In i?. glaucostigma, the rostral outline 

 is slightly concave from its base to near the tip, where it becomes convex, thus 

 making the terminal portion of the snout broader and more bluntly rounded. The 

 posterior gill-slit is narrower, contained If times in the fourth slit. In other 

 details of structure, the two forms agree very closely, the proportions of disk and 

 fins, the size of eyes, nostrils, and mouth, and the character of nasal flaps being 

 wholly similar. 



B. glaucostigma has been considered the northern representative of R. 

 leucorhynchus, but is now recorded from the Bay of Santa Helena, near Guayaquil 

 (Boulenger, 1898-9, Vol. XIII, p. 1). Its discovery at Panama is therefore to be 

 expected. 



