814 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



period, of the type, which is one of the highest among the true fishes. 

 It probably belongs to the Percidw, although I have not ascertained the 

 presence of teeth on the vomer, and there may be eight branchiostegal 

 rays. As . compared with the genera, recent and extinct, which are 

 allied to Ferca, it differs in the unarmed operculum and the preopercu- 

 lum with teeth only on the lower limb, and in the presence of but two 

 anal spines. It is therefore a weaker form than they, and, though of a 

 higher type, less strongly protected by spines than the cotemporary 

 Asineops. Mioplosus embraces the largest Physoclystous fishes yet 

 known from this formation, and specimens are not rare at the locality 

 from which they have been procured. They are often in a state of ex- 

 cellent preservation. The type of the genus is the ilf. labracoides. 



Char. spec. — The M. ahhreviatus is represented by but one specimen, 

 from which the muzzle has been broken away. It is the stout species of 

 the genus, and the others succeed it in this enumeration in the order of 

 their greater elongation of form. The depth at the first dorsal fin enters 

 the total length (including caudal fin) three and a half times ; and the 

 depth at the first anal ray enters the length of the vertebral column 

 two and eight-tenths times. Vertebrae visible behind clavicle: D. 9; 

 C.14. Eadii: D. IX— I. 11; A. II— 11; P. 14. Ventral with a very weak 

 spine. The last dorsal spines, as in all the other species, are very short, 

 the anterior ones slender and moderately long ; in this species, they are 

 curved. The anal spines are short and slender, the first a rudiment. 

 There are six rows of scales above and six below the vertebral column 

 on the caudal peduncle. 



Measurements. 



M. 



Leugth of vertebral column 0.125 



Length of third dorsal sx)ine 0.025 



Length of ninth dorsal spine 0.007 



Depth at middle of first dorsal fin , 0.060 



Depth of caudal peduncle 0.025 



Mioplosus labracoides, sjh nor. 



. This Perch is represented by five specimens, mostly in good j^reserva- 

 tion. They have much the proportions of the Eock-fish. The origins of 

 the pectoral and ventral are in nearly the same vertical line, and that 

 of the first dorsal is not far behind them. That of the first ray of the 

 anal is below the second or third ray of the second dorsal. The rays of 

 none of the fins are prolonged ; the dorsal spines are slender and nearly 

 straight, the longest (third), when depressed, reaches but four-tenths the 

 distance to the first ray of the second dorsal. The last dorsal spine is 

 very short. The soft dorsal rays are rather longer than the spinous. 

 Formulae :— Bays : D. IX— 1. 12 ; C. S— 17— 8 ; A. 11—14 ; V. I. 5. Verte- 

 brte : D. 10 ; 0. 15. 



The depth at the first dorsal fin enters the total four times ; the depth 

 at the first anal ray enters the length of the vertebral column three times. 



