132 Memoir Sears Foundation for Marine Research 



Benthobat'ts cervina Bean and Weed, Proc. U. S. nat. Mus., j6, 1909: 679 (descr., color, meas., size, cf. B. 

 moresiyi Alcock; continental slope off N. Florida, 373 fath.); Garman, Mem. Harv. Mus. comp. ZooL, 

 36, 191 3: 295 (descr. after Bean and Weed, 1909). 



Suborder RAJOIDEA 

 Skates and Their Immediate Relatives 



Characters. Head and body anterior to axils of pectorals strongly flattened dorso- 

 ventrally. Snout neither produced as a long flat blade nor with lateral teeth; anterior 

 sides of head without separate fin-like expansions of pectorals. Tail sharply marked off 

 from body sector; moderately slender in most cases but extremely so exceptionally; 

 with or without dermal folds along its sides. Pectorals united with sides of head nearly 

 or quite to tip of snout, the whole forming a thin flat disc ranging in shape from sub- 

 circular to more or less rhomboidal. Two dorsal fins, with cartilaginous rays,^ excep- 

 tionally one or none; first much closer to tip of tail than to tips of pelvics. Caudal 

 reduced to a small membranous fold, sometimes lacking in adults. Outer margins of 

 pelvics more or less concave or notched, weakly so in some but so deeply so in others 

 that anterior division of fin forms a separate limb-like structure; inner margins of 

 pelvics either free or attached to sides of tail to their tips. Teeth numerous, rounded, 

 or with conical cusp. Pelvis approximately straight, a prepelvic spur at each corner. 



Upper surface of disc more or less rough with prickles or thorns in most cases, 

 but perfectly smooth in some. 



Front of cranium with a single unbranched rostral process, or none; antorbital 

 cartilages not extending forward to help support anterior part of disc; tips of branchial 

 rays not expanded as rounded plates. Pectoral, pelvic and dorsal fins without horny 

 rays (ceratotrichia), the cartilaginous radials extending outward to margins; caudal 

 membrane without radial supports. Surfaces of gill arches, inward from gill filaments, 

 either smooth or with minute fleshy knobs. Spiracle with vestiges of gill folds. 



Families. The great majority of the members of this extensive suborder so closely 

 resemble one another that they are united by common consent in a single family, the 

 Rajidae, typical Skates. However, three genera depart from the typically rajid con- 

 formation. Two of these, Anacanthohatis and Springeria, differ in that they have: a per- 

 fectly smooth upper surface, no dorsal fins, pelvics attached to sides of tail nearly or 

 quite to their tips, whip-like tail with membranous caudal, and snout produced at the 

 tip as a soft filament ; the other, Arhynchobatis, differs in having only a single dorsal fin 

 and a caudal that is larger than that of any other Skate.^ These features seem important 

 enough to warrant the institution of the family Anacanthobatidae for the reception of 

 Anacanthohatis and Springeria and of the family Arhynchobatidae for Arhynchobatis, 

 but with the reservation that the need for the latter would vanish should it prove that 

 the single known specimen of its type genus was abnormal as regards the number of 

 dorsal fins. 



1. The type specimen of Raja garmani has three dorsals, an interesting reduplicative abnormality (p. 204). 



2. See Waite (Rec. Canterbury [N. Z.] Mus., i [2], 1909: 150, pi. 20) and Whitley (Fish. Aust., /, 1940: 192, fig. 221) 

 for description and photograph of the unique specimen of Arynchobatis asperrimus Waite. 



