COTTIM. LXXIII. 149 



bb. Preopercular spines small, mostly concealed by the skin ; skin smooth 

 or prickly in or behind the axil only. (Potamo coitus Gill.) 



406. C. richardsoni Agassiz. MILLER'S THUMB. BLOB. 

 MUFFLE-JAW. Body rather stout, the head very broad; pre- 

 opercle with a short, sharp, straightish spine, turned upward and 

 backward, with 2 smaller spines below it. Olivaceous, much barred 

 and speckled. Head 3; depth 4 to 6. D. VI to VIII -16. A. 

 12. V. I, 4. L. 3 to 7. Lake Superior to Ark., Ga., Md., and 

 Canada very abundant in springs, caves, cold lakes, and rocky 

 brooks. Very variable. The numerous varieties or nominal spe- 

 cies are hardly worthy of recognition by name. (To John Rich- 

 ardson, author of the " Fauna Boreali- Americana.") 



aa. Palatine teeth, none; V. I, 3; skin mostly smooth. (Coitus. 1 ) 

 c. Anal rays 13 or 14. 



d. Preopercular spine large, hooked upward. 



407. C. pollicaris (Jordan & Gilbert). Light olive, blotched 

 and spotted with black, but not speckled ; upper fins spotted. Eye 

 5 in head. Head 3| ; depth 4f. D. VII -19. A. 13. L. 5. 

 Lake Michigan. (Lat., thumb-like.) 



408. C. spilotus (Cope). Olive, everywhere closely speckled 

 with darker except on belly; sides barred with blackish; fins 

 barred and spotted. Eye 4 in head. Head 3 ; depth 5. D. 

 VIII -17. A. 13. L. 3. Grand Rapids, Mich. (o-TTtAomfe, 

 spotted.) 



dd. Preopercular spine short, acute, turned obliquely upward. 



409. C. viscosus Haldeman. Stout, with many mucous pores ; 

 fins low. Olivaceous, body and fins mottled with dark ; 1st D. with 

 red edge. Head 3 ; depth 4f. D. VI -18. A. 14. Penn. to Md. 



cc. Anal rays 11 or 12. 



e. Preopercular spine short, scarcely hooked. 



f. Preopercular spine bent upward and backward. 



410. C. gracilis Heckel. Body rather slender ; fins large. Oliva- 

 ceous, mottled, 1st D. edged with red. Head 31 ; depth 4^ to 5^. 

 D. VIII -16. A. 12. L. 4. N. Eng. and N. Y. (Var. gobioides 

 Grd., with robust body, and var. boleoides Grd., with slender body 

 and long fins, have been described.) (Lat., slender.) 



ff. Preopercular spine directed backward and scarcely upward. 



411. C. hoyi Putnam. Slender; 9 prickly above; jaws nar- 

 rower and mouth smaller than in C. gracilis ; another spine below 

 it turned downward, and one or two others still lower. Olivaceous, 

 speckled and barred. D. VI -15. A. 11. L. 2. L.Michigan. 

 (To Dr. Philo R. Hoy.) 



ee. Preopercular spine distinctly hooked. 



1 The species of this group have never been critically studied ; some of them are 

 doubtful, and most of them may prove to be mere varieties of Coitus gracilis. 



