LYGISMA 13 



haemal spines strong, interhsemals, interneurals and fins lost; head large, 

 with large orbit, median in position; lower jaw prominent; pectoral in- 

 serted low. Vertebras about 40, reduced posteriorly, longer than deep and 

 constricted. No scales or scutes preserved. 



We identify this specimen doubtfully by the tough and twisted 

 spinal column, which seems to be a distinctive trait. 



No. 121 shows the head with some of the vertebrae, of the same 

 species. 



Family SCOMBRID^ 



Next to the evidence of the extraordinary catastrophe which over- 

 whelmed the herring known as XYNE GREX, the most remarkable feature 

 of the Lompoc beds is the presence of five different species of mackerel 

 predatory fishes, doubtless lured into the bay to feed on the herring. 



All of these forms are related to the living species known as 

 Spanish mackerels, SCOMBEROMORUS Lacepede (CYBIUM Cuvier). But 

 differences in the vertebral column, the dentition and the interspinal bones, 

 necessitate the recognition among them of four distinct genera. To 

 these, we assign the names of TURIO (WILBURI), THYRSION (VELOX), 

 THYRSOCLES (KRIEGERI), and OCYSTIAS (SAGITTA). 



The six genera of SCOMBRHLE found in the Miocene deposits of 

 Southern California may be thus compared with each other and with the 

 living genera of this type. 



(a) Anterior vertebrae simple, not "trellis-like"; teeth not serrate, nor 

 greatly enlarged ; posterior vertebrae not held immovable by backward ex- 

 tensions from apophyses ; no canine teeth ; body without corselet of modi- 

 fied scales, as far as known. 



(b) Vertebrae few, about 28 in number; dorsal spines about 10 in 

 number, slender, close-set. (Allies of SCOMBER.) 



(c) Interspace between dorsals short, not more than the length 

 of two vertebrae ; body rather deep, tapering backward ; the depth about 

 31/2 m length ; teeth unknown ; opercular region short. TUNITA. 



(cc] Interspace between dorsals long; as long as four or more verte- 

 brae ; body elongate, tapering slowly backward ; depth about 4% in length ; 

 interhaemals slender and short, weak. 



(d) Opercular region moderate, teeth unknown (supposedly conic 

 and pointed, close set). AUXIDES. 



(bb) Vertebrae about 28; dorsal spines about 20. Opercular region 

 very long, longer than distance from front of eye to edge of preopercle ; 

 teeth compressed, wide set, about 20/20 on each side; body moderately 

 elongate, the depth about 5 in length; dorsal spines slender, close-set, the 

 anterior elevated. (Ally of EUTHYNNUS.) TURIO. 



