’ 
522 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 
band of dark brown; between this and another dark band which crosses 
the bases of the ridges there is a ight 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 bands. 
These are more distinct in the young. With the exception of a dark 
spot on the posterior angle of each pectoral, 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 
satisty myself of the identity of Trigonorhina alveata, described from 
old, and Platyrhina exasperata, from very young specimens. 
Southern California. 
PLATYRH INOIDIS, 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. Viviparous. 
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 viviparity. 
Platyrhinoidis triseriata. 
Jord. & Gilb., 1880, Proc. U. S. Nat. Mus. 36. 
Disk, including ventrals, subrhomboid, a little longer than broad, 
anterior borders convex, anterior and lateral extremities forming broad 
eurves. Snout broad, rounded in front, length from upper jaw equal 
to distance between outer borders of nostrils. Rostral cartilage stout, 
ridges approaching rapidly and meeting near the end to form an acute 
point. Spiracles moderate, larger than the eyes and close behind them, 
without folds on the sides. HKyes 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 the 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 
in advance of the middle of the tail, posterior reaching a little behind 
the insertion of the caudal. Tail strong, more distinct from body than 
