374 



D. 8. P. R. E. EXP. AND SURVEYS — ZOOLOGY — GENERAL REPORT. 



ring at the base of pectorals inclosing a large snb-circular black spot. Beneath dull yellowish 

 white ; the external margin of the ventrals being blackish. The dorsal fins are olivaceous ; 

 the extremity of the tail blackish with a lighter margin. 



Family MYLIOBATIDAE, Owen. 



The rays of the i^ctoral fin.? disappear altogether on the sides of the head, but develop again 

 in front of it, constituting a kind of cephalic fin, which forms the anterior extremity of the 

 disc. The head, therefore, from the region occupied by the spiracles forwards, is separated 

 from the discoid body ; it is likewise more developed than in the other families of this sub-order. 

 The na.'i.il flaps of either side coalesce into a quadrilateral, posteriorly fringed membrane, or 

 lip, wliich extends to the mouth. The nasal apertures api)roximate interiorly, being separated 

 by a narrow frenum, which tapers away towards the angles of the mouth. The latter is 

 straight. The dentated portion of the jaws extends deep inwardly. The teeth are large, 

 depressed, mosaic pavement-like. The upper maxillar membrane extends from tlie palate and 

 the cheeks outwardly, it being very long, with a convex margin, which is fringed upon its 

 middle. The lower maxillar membrane is close to the dental margin. Behind these membranes 

 may be observed some papillae still. The eyes and the spiracles are situated on the side of 

 the skull ; the spiracles being separated from the eyes by a wide bridge. The eyelids are 

 wanting. The tail iselongated, flagelliform, with a dorsal fin at its base, and a depressed 

 spine behind the latter, directed horizontally backwards. 



^\-K.—iViiliohatini, EoNAP. Syst. Vertebr. 1837, 44; &, Selach. Tabul. analyt. 1838, 3.— Bil. Iconogr. Encycl. II, 1850, 243. 

 Mi/liobatides, Mull. & Henle, Syst. Beschr. Plagiost. 1841, 176.— Mull, iu M'iegm. Archiv fiir Naturg. 1845, I, 137. 



Dii.M. Ichthyol. analyt. 1856, 145. 

 Myliohalidae, Owen, Lcct. Comp. Anat. Vertebr. Anim. 1846, 51. 



The Myliobatides are quite numerous along the Atlantic coast of the United States, where we 

 find species of Myliolatis, of Aiitohatis, and BMnoptera, the chief represenlatives of this family. 



RHINOPTERA, Kuhl. 



Gkn. CiiAii. — Snout more or ks.s eniaiginatcd anteriorly. The cranial fin not in a some level with the pector.d.^, being 

 directed more downwards, and fixed to the inferior edge of the base of the pectorals. The rays of the cranial fm begin, 

 likewise, more backwards than the termination of the rays of the pectorals. The lower edge of the nasal (lap is straight, 

 whilst its exterior angle is pointed. On the dorsal surface a longitudinal fissure on either side. Either margin of the jaws 

 straight. The teeth are broader than long, hexagonal, depressed, placed side by side, constituting from three to five series, 

 diminishing in size laterally. Alongside and exteriorly to the former there are n few series of smaller teeth, not broader 

 tliau long ; they occupy tlie entire width of tlie jaws. 



Syh. —Ji/miojiltra, Kimil,— Mill. Vergl. Anat. Myxin. I, .1836, 7G.— Mill & Henle, Syst. Beschr. Plagiost. 18J1, 

 181.— DeKay, New Y. Faun. IV, 1842, 375,— Stoiier, Synops. 1846, 263.— Drji Ichthyol. analyt. 1856, 

 145. 



Whenever an opportunity .shall be afibrded us for comparing the species from our Atlantic 

 coast to the one recorded hereon, wc may be better prepared in pointing out the characters which 



