98 TELEOSTEI : PEKCKSOCES. XIX. 



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

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

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

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

 lono-er, longer than innnominate bones, arfd other trifling differences. 



110. GASTEROSTEtrS (Artedi) Linnsus. 

 (yaa-Tqp, belly; ocrreov, 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. gymnurua Cuvier. Tail keeled. Grayish, dotted. 

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

 (G. dimidiatus Reinhardt.) (Eu.) {yvfivos, naked; ovpa, 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. 1|. Maine. (To Charles G. Atkins, 

 Fish Commissioner of Maine.) 



aa. 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 ; operoles striate ; rugose plates at base 

 of spines ; spines serrate. Head 3^; depth 4^. D. 11-1,13. A. 

 I, 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. APELTES DeKay. (a, privative ; TreXxT;, 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 Acanthopteri, 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 (OpMocephalidce) wanting. (Lat., 



