Cocker ell — Scales of Panama Fishes. 153 



[Circiili not angulate in median line above nucleus ; scales larger. 

 Xiphophorus helleri Meckel. (Obispo, Mexico; S. E. Meek).] 



15. Apical margin with a single row of sharp teeth, and no ctenoid ele- 



ments below them ; nucleus just below apical margin 16. 



Apical field with one or more rows of ctenoid elements below the 

 marginal teeth 19. 



16. Scales with rounded base (Pleuronectidse) 



Citharichthys spilopterus Gthr. , upper side. 



Scales with truncate base, the laterobasal corners evident ; apical 



margin usually like the transverse section of a roof of a house 



(Gobiida?) 17. 



17. Basal radii about 7 to 9 Chonophorus nelsoni Evermann 



(Rio Culebra. ) 

 Basal radii more numerous 18. 



18. Scales 2.5-3 mm. long Philypnus maculatus (Chepo.) 



Scales less than 2 mm. long . . Eleotris pisonis Gmel. (Porto Bello.) 



Gobius claytoni. (Mindi.) 

 Gobius soporator C. & V. (Fox Bay, Colon.) 



19. Scales conspicuously longer than broad, parallel sided 20. 



Scales broader than long, or at most a little longer than broad . . 22. 



20. Scales minute, much less than 2 mm. long; nucleus never elongate, 



always subapical (Soleidse) 21. 



Scales larger, at least over 2 mm. long; nucleus often elongated, and 

 then radii not reaching middle of scale; apical teeth often trun- 

 cate (Serranidee) . Petr ometopon panamensis Steind. (Tabogal. ) 

 Bodianus acanthistius Gilbert. (Panama market.) 

 Mycteroperca xenarcha Jordan. (Corazal.) 

 Paranthias furcifer C. & V. (Taboga I.) 



21. Scales more or less narrowed apically ; radii 3 to 5 



Achirus fluviatilis . both sides (Rio Chorera.) 

 Scales not narrowed apically ; radii very many 



Symphurus plagusia B. & S. both sides (Fox Bay, Colon.) 



22. Basal radii few (4 to 6), and widely spaced; subapical ctenoid ele- 



ments brick-like (MuUidse) 



TJpeneus maculatus ^\och. (Fox Bay.) 



Basal radii many, or at least closer together, usually arranged in 



fan-like manner ; subapical ctenoid elements not brick-like . . 23. 



23. Scales minute, 1.5 mm. or less long; only about three rows of distinct 



ctenoid elements below the marginal teeth (Sciaenidse) 



Menticirrhus martinicensis C. & V. (Fox Bay.) 

 Scales larger 24. 



24. Elements of ctenoid patch triangular, feebly developed, with no 



sharp salient marginal teeth ( Xystaematidse ) 



Eucinostomus californiensis Gill. (Mindi Cut.) 



Elements of ctenoid patch well developed; marginal teeth salient, 



narrow and sharp, or (Stellifer and Orthopristis) often slightly 



bifid 25. 



