MR. E. T. niOGINS ON THK OTOLITES OIT FISH. 165 



examined more than 3700 fish, representing nearly 450 species, 

 and never yet, save in the instance of the Carp Bream, found any 

 abnormal form which could create a difiiculty in identifying a 

 species if ever seen before. In some closely allied species I must 

 admit that the distinctive marks are very slight, but sufficiently 

 characteristic to make their separation and identification a matter 

 of no great difficulty. 



1. In the Percidae. The central otolite is more or less oblong 

 (as in Perca, Labrax, and JPolyprion) ; oval, posteriorly acuminate 

 (as in Acerina, Tracliinus, &c.). 



2. In the Grurnards. Almost circular, with a slight furcation, 

 margins indented. 



In Cotti. Long and narrow, tapering at each end. 

 In Gasterostei. Smooth and rounded. 



3. In the Sparidse. Yery concavo-convex, margins, especially 

 the inner, deeply indented, tapering considerably at either end. 



4. In the Scombridse. Eurcate (as in Scomber and Caranx) ; 

 stellate (as in Zeus) ; irregulai'ly pisiform (as in Capros). 



5. In the Tsenidse. Elongated (as in Sepola) ; very deeply con- 

 cave, the inner and outer margins bent inwards (as in Trichiurus) . 



6. In the MugiHdae. Very concave, margins indented ; width 

 nearly equal. 



7. In the Grobioidse. Furcate (as in the Blennies and Anar- 

 rJiicTias) j globular (as in the Gobies) ; elongated (as in Callionymus). 



8. In the Lophiidse. Outer margin semilunar, inner denti- 

 culated. 



9. In the Cyprinidse. Subglobular, cuneate posteriorly, the de- 

 gree of cuneation being specific. 



10. In the Esocidae. Eurcate, inner margin denticulated (as in 

 Msooo) ; elongate and oval (as in Belone, Semiramjjlnis, &c.). 



11. In the Siluridse. Subglobular and mammillated (as in Cal- 

 licMliys) ; pisiform (as in Silurus). 



12. In the Salmonidse. Eather triangular, anteriorly acuminate 

 (as in Salmo) ; posteriorly furcate, denticulated below, and slightly 

 acuminate anteriorly (as in Cor eg onus). 



13. In the Clupeidse. Posteriorly furcate and truncate, ante- 

 riorly rounded and indented. 



14. In the G-adidae. Thick, mammillated ; pyriform, or elongate 

 oviform (as in MorrJiua) ; elongated and tapering (as in Motella). 



15. In the Pleuronectidse. Nearly flat, oval, rounded, quadrate 

 or truncate. 



