158 Memoir Sears Foundation for Marine Research 



pectorals back to first dorsal and followed by prickles as far as second dorsal; skin of 

 disc and tail naked otherwise except for a few minute prickles opposite orbits and 

 spiracles and along edge of disc on male abreast of alar spines. Adult male with two rows 

 of alar spines;'" also a patch of about 18 thorns on either side in malar region abreast 

 of eye and'spiracle. Lower surface of larger specimen (male) prickly from tip of snout 

 rearward to a little beyond midlevel of nostrils and along margins of disc to level of 

 mouth, but otherwise naked on disc and tail; smaller specimen (female) smooth every- 

 where below. 



Snout in front of orbits about 3.0-3.5 times as long as distance between orbits; 

 about 1.6—2.0 times as long in front of mouth as distance between exposed nostrils. 

 Orbit about 1.5 times as long as spiracle; distance between orbits a little greater than 

 length of orbit. Length of first gill openings about V4 as great as width of mouth, the 

 fifth gill openings about 70 "/o as long as the first; distance between first gills 1.5-1.8 

 times as long as distance between exposed nostrils; distance between fifth gills about 

 as great as distance between nostrils. Both nasal curtain and expanded posterior (outer) 

 margin of nostril fringed. Mouth a little bowed in adult male, less so in female. 



Teeth ^ in adult male, in transverse series, with thorn-like and somewhat recurved 

 cusp on circular or oval base, the uppers and lowers alike; ^ series in female, arranged 

 in quincunx, the median teeth with low cusp, the outer teeth without cusp. 



Dorsal fins about equal in size, with convex anterior margin and well rounded 

 apex; base of first dorsal about 87 "/o as long as distance between spiracles. Interspace 

 between first and second dorsals about V2-V3 (50-66 "/o) as long as base of first dorsal. 

 Pelvlcs moderately concave outwardly, weakly scalloped; anterior margin about ^/g as 

 long as distance from pelvic origin to rear tip; anterior lobe narrow, outer margin of 

 posterior lobe weakly convex, rear tip well rounded even In adult male, reaching back 

 about V3 the distance from origin of pelvic to tip of tail. Claspers of adult male reaching 

 a little more than halfway from tip of pelvic toward first dorsal fin. 



Anterior rays of pectorals reaching about ^/j the distance from level of fronts of 

 orbits toward tip of snout. 



Color. Upper surface pale yellowish brown, sprinkled with small indefinitely out- 

 lined darker and lighter spots and pale patches; a dark oval ocellar spot with pale 

 margin on inner part of each pectoral a little posterior to axis of greatest breadth. Lower 

 surface white without dark markings. 



Size. The type specimen, a male 410 mm long, appears to be mature sexually. 



Developmental Stages. The egg cases have not been seen. 



Habits. Nothing is known. 



Range. So far known with certainty only from the Yucatan Bank and near there 

 in Lat. 22°o8' N, Long. 86°53' W, and from southern Florida." Skates have also 



70. On this particular specimen there are five alar spines in the outer row on the left-hand side but only two in the 

 outer row on the right-hand side. 



71. A third specimen of R. ackleyi was sent to us for identification by Stewart Springer. It was a female, 404 mm 

 long, caught off the Dry Tortugas in Lat. 25°03' N, Long. 82^56' W, in 25 fathoms, January 19, ig^i, 

 Oregon St. 233. 



