142 Bulletin American Museum of Natural History. [Vol. XXXV, 



Rhinobatid.e. Guitar Fishes. 

 Rhinobatis productus Ay res. Guitar Fish. 



East Side of Cerros I., March 12; Port San Bartholome, March 13 and 

 again on April 23, and Agua Verde Bay, April 1. Taken on hand-lines and 

 with the seine. 



Rajid.e. Skates. 



Raja microtrachys sp. nov. 



Fig. 1. 



Cartilages weak, notably those of the snout, and structure generally loose. A 

 deep water form allied to isolraehys and trachura, but lacking the mid-dorsal tubercle, 

 with more white below and with other minor differences. Probably closely related 

 also to the cotype of R. aguja Kendall and Radcliffe, Mem. Mus. Comp. Zool., Vol. 

 35, No. 25, pi. i, fig. 2. 



Disk rhomboid, width about 1.2 times length to end of pectorals. Anterior 

 edges meeting in an angle a little greater than 90 degrees, but slightly sinuated so 

 that the angle of the snout is less than 90 degrees. On the hinder part of the snout 

 the margin curves outward and is again somewhat incurved back of the spiracles. 

 Outer and hinder angles of the pectorals broadly rounded, outer margin nearly 

 straight. Snout moderately produced and pointed, the tip blunt, about 3.75 in 

 length to posterior edge of pectoral. Tail from vent a little longer than the rest of 

 the body, depressed, the lower surface nearly flat, with dermal keels posteriorly which 

 are broad and fin-like near the end of the tail. Dorsal fins far back, contiguous (the 

 margins too much broken to permit the form to be determined), origin of first dorsal 

 a distance from the caudal equal to 1.4 in the snout. Pelvic fin deeply notched, 

 separating a pointed fleshy anterior lobe which, measured from the bottom of the 

 notch, is 2.6 in snout. 



Orbit 4 in snout, interorbital the same, concave. Spiracle 1.5 in orbit. Preoral 

 distance slightly greater than snout; mouth straight, 1.6 in preoral distance, equal 

 to internarial space. Mesial nasal flaps large, the hinder limb with a fringe of broad, 

 mostly bifid, papillae, directed forward. Corners of mouth guarded by well-devel- 

 oped flaps; other flaps at the outer posterior margins of nares. Teeth small, with 

 flat crowns and with backwardly directed cusps on their hinder margins. 



Upper parts everywhere roughened with fine stellate, prickles, these smallest and 

 sparsest on the bases of the pectorals, largest and most closely set on the base of the 

 tail and fine and close set between the eyes. Twenty strong retrorse tubercles on 

 mid vertebral line between anterior pelvic lobes and origin of first dorsal, one or two 

 of these spines apparently missing from spaces at middle of tail and again half way 

 between this and origin of dorsal. No other tubercles anywhere. Anterior lobe of 

 pelvic fin and entire under surface smooth, with the exception of a few scattered 

 prickles along the ventral margins of the tail basally. 



Color in spirits dark chocolate brown above, the margins narrowly darker, 

 spiracles pale; underside slate colored, darker toward the margins of pectorals ami 



