522 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



baud of dark browu ; between this and another dark band which crosses 

 the bases of the ridges there is a light band. A dark band across the 

 head between the eyes is somewhat confluent with the band in front of 

 it, which makes the fore part of the head dark, but leaves the promi- 

 nences in front of the eyes light colored. The remainder of the upper 

 surface is more or less clouded by faint indications of transverse bauds. 

 These are more distinct in the young. With the excei)tion of a dark 

 spot on the posterior angle of each x^ectoral, the lower surface is white. 



Total length 33.4, snout to end of ventrals 18, snout to mouth 4.1, and 

 width of disk 15.5 inches. Specimen described an adult male. The 

 kindness of the officers of the National Museum has enabled me to 

 satisfy mj^self of the identity of TrigonorJiina alveata, described from 

 old, and Platyrhina exasperata^ from very young specimens. 



Southern California. 



Platyrhinoidis, gen. nov. 



Disk broad, flat, rounded. Tail moderate, depressed, caudal fin broad. 

 Dorsals posterior. Tubercular spines in vertebral series and on anterior 

 margins of pectorals. Labial fold well developed. Nasal valves not 

 reaching the mouth, posterior lobe rudimentary. yivij)arous. 



Distinguished from Syrrhina and Trigonorhina by the labial fold, 

 nasal valves, and marginal series of spines, and from Platyrhina by 

 the fold, valves, separation of pectorals, and vivij)arjty. 



Platyrhinoidis triseriata. 



Jord. & Gilb., 1880, Proc. U. S. Nat. Mus. 30. 

 Disk, including ventrals, subrhomboid, a little longer than broad, 

 anterior borders convex, anterior and lateral extremities forming broad 

 curves. Snout broad, rounded in front, length from upper jaw equal 

 to distance between outer borders of nostrils. Eostral cartilage stout, 

 ridges approaching rapidly and meeting near the end to form an acute 

 l)oiut. Spiracles moderate, larger than the eyes and close behind them, 

 without folds on the sides. Eyes small, distant from the end of the 

 snout one and one-fourth times the distance between the spiracles. 

 Crown broad, concave. Nostrils broad, narrower than the distance be- 

 tween, which is nearly four times the space between them and the mouth. 

 Nasal valves medium, hardly reaching upon tlie space between the 

 nostrils, outer lobe narrow, posterior rudimentary. Mouth not large, 

 moderately curved, distant from the end of the snout about one and 

 one-third times its width. Teeth small (82 series in the upper jaw of 

 the adult female described), subhexangular on the base, smooth or with 

 alow, blunt cusp. Pectorals separated from the rostral cartilage by a 

 translucent space. Dorsals similar, longer than high, separated by one 

 and one-half times the length of their bases, insertion of anterior a little 

 iu advance of the middle of the tail, posterior reaching a little behind 

 the insertion of the caudal. Tail strong, more distinct from body than 



