NATURAL SCIENCES OP PHILADELPHIA. 245 



nearly uniformly low dorsal and anal fins, and consequently excludes Pime- 

 lepterus tahmel Riippell, P. Dussumieri C. et V. and P. raynaldi C. et V., in 

 which the soft parts of the dorsal and anal fins are much elevated. It is 

 therefore proposed to refer them to a distinct genus under the name of Opis- 



THISTIUS. 



The Pimelepterus waigensis has been stated by Cuvier and Valenciennes to ap- 

 parently have five or six pyloric caeca.* In the species of our eastern coast which 

 I have examined, as well as in T. fuscus <ind Opisthistius tahmel, they are pres- 

 ent in very great number. There is, therefore, an anomalous range of varia- 

 tion for so very closely related species, or appearances have been deceptive to 

 Messrs. Cuvier and Valenciennes. In two specimens of the very closely re- 

 lated P. analogic^ opened by us, the intestines were completely decayed, al- 

 though the fishes were externally in a fine state of preservation. 



The Pimelepterus lavifrons of Tschudi is not at all related to this genus. 



Pimelepterus analogus Gill. 



The greatest height enters 2.6-7 ("35) times in the extreme length. The 

 head forms about two-nintbs (*22) and equals the length of the caudal; the 

 snout enters three times in that length, and is less than the width of the in- 

 terorbital area (*08^) : the median rays of the caudal are half as long as the 

 longest, and rather more than half as long as the head ('Hi.) The dorsal is 

 highest at its sixth spine, the length of which enters eleven times (*09) in the 

 total, and is twice as great as the last spine ; the greatest height of the soft 

 portion equals a quarter of the head's length (-05 J.) The pectorals and ven- 

 trals have the same length, and are contained more than eight times ("12) in 

 the total. 



D. XL 14. A. III. 13. C. 1. I. 7. 6. I. 1. P. 2. 14. V. 1. 5. 



The teeth are about twenty-two in number in each jaw. The vertical part in 

 the adult is as long as the heel or horizontal part, and the apex subtrian- 

 gular. 



13 



Scales 75 

 20 



The color of the adult is grayish on the back, and on the flanks indistinctly 

 longitudinally banded alternately with yellow and grayish or silvery, the 

 former along the middle of the scales, and the latter along the adjoining sides. 

 In the young, large yellowish spots are distributed on the body. The preor- 

 bital is silvery. The fins are rather dark. 



Nearly related to Pimelepterus waigiensis (Quoy and Gaimard) and P. 

 incisor C. et V., but apparently differing slightly in its proportions. 



Family GERREOIDJE Blkr. 



Subfamily GERREINJ3 Blkr. 



Genus Diaptekus (Ranzani.) 



DlAPTERUS CALIFORNIENSIS Gill. 



The greatest height nearly equals a third ( - 32) of the extreme length ; the 

 caudal peduncle is slender and attenuated at the middle. The head forms 

 less than a quarter ( - 22) of the length ; the diameter of the orbit enters two 

 lines and two-thirds (-09) in the head's length, the snout three times and a 

 third. The interorbital area is flattened, and the groove for the posterior pro- 

 cesses of the intermaxillary bones is broad, scaleless, semioval between the 

 eyes, and attaining to the vertical of the ends of the maxillary bones ; the ex- 

 posed portions of the latter bones are convex above, semicordate, and twice as 

 long as broad. The lateral line is sigmoidally curved. 



* " Le nombre des coecums qui entourent le pylore nous a paru de cinq ou six." 



1862.] 



