394 THE PLAGIOSTOMIA. 



dermal fold below and a weaker one above behind the spine. Small scales in a 

 longitudinal band above each eye, along the vertebral column, and grouped near 

 the middle of the disk. Compressed backward directed tubercles in a vertebral 

 series from the caudal spine forward. Length of disk, to behind the vent, 

 33 cm. and width 28 cm. in the type, a mature male from Shanghai. 

 Back chocolate-brown. 



Dasybatus fluviorum. 



Dasyatis fluviorum Ogilby, 1908, Proc. Roy. soc. Queensland, 21, p. 6. 



Disk subcircular, length eight ninths of the width; front angle obtuse, 

 with tip slightly produced; hind borders fully and inner moderately convex; 

 outer angles broadly and posterior somewhat narrowly rounded. Jaws undu- 

 lated, upper biemarginate. Floor of mouth with seven papillae, arranged in 

 three groups: — on each side a pair, of which the inner is the larger, the outer 

 sometimes absent or undeveloped, and three in the middle more conspicuous 

 and truncated. A group of small blunt tubercles above each spiracle, a trans- 

 verse row of three tubercles behind the occiput from behind the median of which 

 a series of retrorse spines extends along the dorsal ridge and is continued on the 

 tail nearly to the base of the caudal spine. One of the median interscapular 

 spines is slightly larger than the others of the vertebral series. Entire scapular 

 region tuberculigerous. Length of tail two and one fourth times that of the disk. 

 The four tubercles of the tail nearest the spine are larger than those of the back. 

 A short fold, deeper backward, behind the caudal spine; another below the tail 

 has its origin below the base of the spine and is much longer and slightly deeper. 



Back olive-brown, margins of disk and of ventrals lighter; bluish white 

 below, pale brown toward the margins; tail black, lower surface and sides of the 

 proximal fourth brown. 



Total length of type about 31.2 inches (794 mm.), snout to vent 9.83, width 

 of disk 10.8, and length of tail 21.2 inches approximately. 



Brisbane River, ranging above the tide waters. 



Dasybatus akajei. 



Trygon akajei Muller & Henle, 1841, Plagios., p. 165, pi. 54, f. 1; Schlegel, 1850, Jap. Pisces, p. 308; 



Bleeker, 1S57, Act. Soc. sci. Ind. Neerl., 3, p. 44; Dumeril, 1865, Elasm., p. 604. 

 Dasyatis akajei Jord. & Everm., 1902, Proc. U. S. nat. mus., 26, p. 319, fig. 2; Jordan & Richardson, 



1910, Mem. Carnegie mus., 4, p. 165, fig. 2. 



Disk rhomboid, anterior margins nearly straight meeting in an obtuse angle 

 at the snout ; width about one fourth more than length of body. Mouth with 



