98 TELEOSTEI: PERCESOCES. XIX. 



no dermal plates, the bones and spines all feeble ; tail keeled. Head 

 3; depth 4. D. IV-I, 10. A. I, 10. L. 2. K Y. to Kansas 

 and Greenland, abundant N. W. in small brooks ; S. to Greensburg, 

 Ind. (Shannon.) Var. caynga Jordan (W. N. Y.) has V. spines 

 longer, longer than innnominate bones, and other trifling differences. 



110. GASTEROSTEUS (Artedi) Linnaeus. 

 (yaa-TTjp, belly; oareov, bone.) 



a. Sides partly covered with bony plates, the tail naked. 

 b. Lateral plates 2 to 7. 



c. Ventral spine without cusp at base; lateral plates 2 or 3. 



240. G. wheatlandi Putnam. No mucous pores; tail com- 

 pressed. Blackish. D. II, I, 10 to 12. A. 1,8. Cape Cod, N. 

 scarce. (To Dr. Richard H. Wheatland, of Salem, Mass.) 



cc. Ventral spine with a strong cusp at base behind; lateral plates 

 about 7. 



241. G. gymnurus Cuvier. Tail keeled. Grayish, dotted. 

 D. II, I, 12. A. I, 8. L. 2. Newfoundland to Greenland, etc. 

 (G. dimidiatus Reinhardt.) (Eu.) (yvpvos, naked; ovpd, tail.) 



bb. Lateral plates 15 ; tail keeled. 



242. G. atkinsii Bean. Slender ; V. long. Head 3^ ; depth 5. 

 D. II, I, 11. A. I, 8. L. l\. Maine. (To Charles G. Atkins, 

 Fish Commissioner of Maine.) 



00. Sides entirely covered with (28 to 33), bony plates; tail keeled; V. spine 



with cusp at base. 



243. G. aculeatus L. COMMON STICKLEBACK. Olivaceous, 

 sides silvery ; back dotted ; opercles striate ; rugose plates at base 

 of spines; spines serrate. Head 3; depth 4^. D. II -I, 13. A. 



1, 9. L. 4. N. Y. to Greenland and Europe, abundant, variable. 

 (Eu.) Perhaps all the preceding are forms or varieties of this. 

 (Lat., bearing prickles.) 



111. AFELTES DeKay. (a, privative : TreXr?;, shield. 



244. A. quadracus (Mitchill). Olive, mottled; males nearly 

 black, the V. red in spring ; body plump, with long slender tail ; 

 skin naked. Head 4; depth 4. D. Ill, I, 11. A. I, 8. L. 2. 

 N. J. to Labrador ; abundant along coast. (Lat., four-spined.) 



ORDER XIX. PERCESOCES. 



This group comprises Physoclysti, which have the general char- 

 acters of the great group of Acantkopteri, but in which the ventral 

 fins are abdominal, the pelvic bone not being attached to the 

 shoulder-girdle. Scales cycloid, opercles unarmed. The spinous 

 dorsal is short and sometimes (Ophiocephalidce) wanting. (Lat., 



