486 PROCEEDINGS OF THE ACADEMY OF 



Spiracles of small size, developed. 



To this group are now referred two genera. 



Genus RHINOTRIACIS Gill. 



Body compressed, elongated and subfu9iform in profile. 

 Scales tricarinated. 



Head oblong, with the snout produced, oblong and attenuated towards the 

 transversely rounded apex. 

 Eyes rather small. 



Mouth moderate and boldly arched in front. The groves at the corners are 

 well defined and the upper lip folds over the lower. 

 Teeth with an acute median proog and a smaller lateral one on each side. 

 Nostrils nearer the mouth than the front of the snout, obliquely transverse 

 and wilh a wide convex flap arising from the anterior or inner border of each 

 aperture. 



Dorsal fins nearly similar in form, obliquely produced upwards towards the 

 anterior angle, which is rounded ; acutely produced backwards from the 

 posterior angle; the first dorsal is iutermediate between the pectoral and ven- 

 tral fins. 



Anal fin similar to the second dorsal. 



Caudal fin with a terminal triangular lobe, and with the membrane above the 

 vertebral column moderately developed; inferior lobe scarcely produced down- 

 wards from the anterior angle. 



Pectoral fin moderate, extensible partly under the first dorsal, rounded at each 

 angle and subtruncated behind. 



Ventral fins trapezoid, rounded at the external angle. 



Rhinotriacis is very closely related to Triads, but is separable from that genus 

 on account of the produced snout, the position of the first dorsal fin and per- 

 haps the greater development of the pectoral fins. It has a superficial resem- 

 blance to the genus Isoplagiodon of the group of Galeorhini produced by the 

 situation of the first dorsal fin and the elongation of the snout, as well as its 

 color, but the dentition, the presence of spiracles as well as the form and rela- 

 tive position of the fins at once distinguish it. 



The only known representative of this genus is Californian ; a single young 

 specimen of the species was sent to the Smithsonian Institution by Mr. Samuel 

 Hubbard, and referred to as a species with the aspect of Isojdagiodon immediately 

 after the Triads semifasdatits. It differs from the species of Triads' in color as 

 well as morphological characters, being uniform reddish-brown above, and 

 greyish-white below, with which color the pectoral, ventral and anal fins are 

 also margined. 



Rhinotriacis henlei Gill. 

 (The following table of measurements will suffice for the identification of the 

 species. It is hoped that older specimens may be obtained in time to prepare 

 a complete description for a work on the Fishes of Western America. The umbi- 

 lical cord of the specimen noticed has entirely disappeared. 



The base of each fin is considered as being on a level with the body ; the 

 height is measured in an oblique direction parallel with the axis of cleavage of 

 the fin; the greatest breadth is parallel with the base or terminal margin, and 

 crosses obliquely the line of cleavage. 

 Extreme length 9}. 



Body Greatest height 10; greatest width 6; height of tail behind anus 4; 

 least height of tail 2J. 



Head Greatest length 18 ; greatest width 12 ; height of snout TJ. 

 Eye Diameter 4 | ; distance from snout 9. 



Mouth Width 6 ; depth from symphysis of jaw to line between corners of 

 mouth 3. 



[Oct. 



