90 BULLETIN OF THE 



Uraptera. 



On Uraptera agassizii (Plate XXVI.) the upper surface is pretty well covered 

 with tubes and tubules. On the ventral aspect the main tubes are all present, 

 but the tubules are few and short. There is nothing in the canals that will 

 distinguish this genus from Raia. 



On the shoulders, the laterals are thrown decidedly outward; farther for- 

 ward, they make a broad curve toward the vertebrae ; and they converge toward 

 the base of the tail. Their tubules are of medium length and are most numer- 

 ous above the abdominal region. The pleurals reach far out on the pectorals, 

 enclosing an area, convex forward, somewhat lenticular in shape. At the angle 

 opposite the shoulder they send back a strong branch with many tubules on 

 its outer side. The most of the pleural tubules pass forward ; a few, espe- 

 cially of those near the anterior border, turn back. Opposite the eye the 

 pleural is connected with the suborbital by several tubules; thence it bends 

 toward the margin and descends about half-way from the orbit. A strong post- 

 scapular goes to the hinder angle of the pectoral ; the greater number of its 

 tubules are directed outward. 



The occipitals are short and greatly divergent. Between the eyes the cra- 

 nials curve toward each other; in front of the orbits they bend apart; and on 

 the rostrum they converge gradually to their points of descent, near the end. 

 Outward from the curve in front of the orbit a tuft of tubules extends from 

 each. The suborbitals take a tolerably direct course to the end of the snout, 

 but pass down some distance before reaching it. 



On the lower surface, the pleurals bend out opposite the first gill cleft and 

 inward opposite the shoulder girdle, in both the backward and the return 

 courses. They neither reach back behind the middle of the abdomen, nor out 

 to the middle of the pectorals. 



The orbito-nasals are elongate, converging in front. The lower suborbitals 

 are only of moderate length, diverging backward. On the greater part of the 

 length of the snout the subrostrals are parallel with the prenasals; leaving 

 the latter finally, they pass outward and then forward to make a close fold on 

 themselves before taking a transverse direction in which they meet the subor- 

 bitals. At the inner edge of the nostril the nasals make a sharp bend, then, 

 converging forward, they unite to form a short longitudinal median. From 

 the median the prenasals at first bend outward rapidly, then converge gradually 

 toward the tip, near which they end without connections. 



The following peculiarities are among the more likely to prove characteris- 

 tic: the shape of the pleural area, the short occipital, the length of the tubules, 

 the closeness of the fold in the subrostrals, and the longitudinal median. 



Raia. 



Raia lavis (Plates XXVII.-XXIX.). Some resemblance is seen in the shape 

 of this species and that of Uraptera, and there is still more in the arrangement 



