14 FOSSIL FISHES OF LOMPOC 



(bbb) Vertebra numerous, 40 to 55, subquadrate, strongly grooved; 

 post-ocular region not expanded, shorter than rest of head ; dorsal spines 

 low, slender. (Allies of SCOMBEROMORUS). 



(<?) Vertebra 40 to 42, rather strong, deeper than long, the depth 

 of one about equal to one-third the distance to the base of the soft dorsal ; 

 opercle strongly striate; interneurals short, slender, and weak. 



(/) First dorsal of about 10 spines ; body rather robust ; teeth conic, 

 pointed subequal, in bands, 35 to 40 on each side of jaw ; depth about 5 in 

 length. THYRSION. 



(//) First dorsal of about 22 slender spines; body very slender, the 

 depth about 7 in length ; teeth unknown. OCYSTIAS. 



(ee) Vertebrae 46 to 48; deeper than long. Interhaemals very long 

 and rather strong, arranged in a parallel grate-like series, reaching about 

 % distance to backbone. Vertebrae 22 + 25 = 47 ; body rather robust, 

 the depth about 5 in length. 



(#) First dorsal of 15 to 20 slender spines; teeth compressed, well- 

 spaced ; probably about 35 on each side. THYRSOCLES. 



(gg) First dorsal of 15 to 18 low, slender spines. 



(A) Teeth scarcely compressed, about 25 in each side; depth S 1 ^ in 

 length. CHRIOMITRA. 



(hh) Teeth much compressed, wide-set, about 12 in each side; inter- 

 hsemals of moderate length, close-set, parallel and nearly straight, depth 

 4y 2 in length. SCOMBEROMORUS. 



Of the other generic names applied to fishes of this group, ACANTHO- 

 CYBIUM Gill (PETUS), with broad, serrated teeth, and the body robust, is 

 well defined. LEPIDOCYBIUM (Gill) (FLAVOBRUNNEUM), with canine 

 teeth, is doubtless also valid. APODONTIS (Bennett) (IMMUNIS), scantily 

 described (teeth conical, wide-set), is probably a typical SCOMBEROMORUS, 

 as is also CYBIUM (Guvier) (COMMERSONI). CHRIOMITRA is, no doubt, 

 a valid genus, with interhaemal as in THYRSOCLES and numerous gill- 

 rakers. 



The fossil genus SCOMBERODON van Beneden (Bull. Acad. Royale, 

 Belgique (2), XXXI, 504-512, 1871) is based on a huge mackerel found 

 in the clays of Rupelian age (Oligocene) at Boom and Rupelmonde in 

 Belgium. It is allied to ACANTHOCYBIUM and remotely to SCOMBERO- 

 MORUS, but its teeth are very large, entire, unequal, and subconic, set in 

 extremely massive jaws. The teeth are relatively few, about 18/18 in each 

 jaw. The caudal vertebrae are remarkable in having a special bone cov- 

 ering, depriving them of all mobility, as in the tunnies. This character is 

 not found in the Miocene genera nor in SCOMBEROMORUS. The species in 

 question, SCOMBERODON DUMONTI, must have reached the length of seven 

 feet (two meters). There seems to be no doubt of the validity of the 

 genus SCOMBERODON. 



