42 FOSSIL FISHES OF SOUTHERN CALIFORNIA 



Caudal broadly forked, its rays about twenty-two, equal and about 

 half greater than depth of body, its lobes slender and strong. Hypural 

 plate evident but short. 



We place this interesting species provisionally in the living genus, 

 THYRSITES of Cuvier, with which it seems to agree fully so far as the 

 parts preserved are concerned. From the type of THYRSITES (ATUN) 

 it seems to differ in the larger caudal fin and possibly slightly longer, 

 soft dorsal and anal. The slender form excludes it from the genus 



SCOMBEROMORUS. 



Family SCOMBRID^E. 



37. Tunita octavia Jordan and Gilbert, new genus and species. 



(Plate XII, fig. 2) 



From the diatomaceous shales at El Modena, Mr. E. E. Hadley 

 has obtained several fragments of a mackerel about a foot in length 

 and having much in common with AUXIDES SANCT.E-MONIC.E already 

 described from the Soledad deposits near Santa Monica. 



The type, No. VII, is a torso about seven inches long, representing 

 the body from the preopercle to the end of the anal, a fish of about 

 a foot in length. The depth is half the distance from the gill opening 

 to the last ray of the anal fin. In this distance about twenty-two vertebrae 

 are included, about twelve in the abdominal region. These have strong 

 spinous processes and short and strong ribs. Body tapering rapidly 

 backward, the depth at last ray of dorsal little more than half that under 

 first dorsal spine; dorsal fin beginning over about the third or fourth 

 vertebra; its spines eight in number, the first being highest, two and 

 a quarter in depth of body. Second dorsal fin beginning close behind 

 the first, barely the length of two vertebrae intervening, of fourteen to 

 sixteen soft rays ; anal fin similar, its insertion farther back, at the end 

 of the first third of soft dorsal; the rays about fourteen; ventral fins 

 well developed, inserted directly below first dorsal spine, somewhat behind 

 the pectorals which are broken; scales rather large for a mackerel, 

 cycloid, not forming a corselet. Bones of head obscure, the broad pre- 

 opercle with radiating ridges obliterated. 



Another example (No. CXXI, from El Modena) shows the head 

 with long oblique mouth, subequal jaws, and with a large plate with 

 strong radiating ridges at the angle of the preopercle as in AUXIDES. 

 The torso ends at the last dorsal spine ; the two ventrals are well shown. 

 Some of the details in our restoration of the head of AUXIDES SANCT.E- 

 MONICE are drawn from this specimen, which proves to belong to a 

 genus distinct from AUXIDES. The small smooth scales of the anterior 



