98 TELEOSTEI : PERCESOCES. — XIX. 
no dermal plates, the bones and spines all feeble; tail keeled. Head 
31; depth 4. D. IV—I, 10. A. I, 10. L. 24. N. Y. to Kansas 
and Greenland, abundant N. W. in small brooks; S. to Greensburg, 
Ind. (Shannon.) Var. cayuga Jordan (W. N. Y.) has V. spines 
longer, longer than innnominate bones, and other trifling differences. 
110. GASTEROSTBEUS (Artedi) Linnzus. 
(yaornp, belly; éar€ov, 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. H, 1,10 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. Il, I, 12. A. I, 8. L. 24. Newfoundland to Greenland, ete. 
(G. dimidiatus Reinhardt.) (Eu.) (yupvds, naked; ovpd, tail.) 
bb. Lateral plates 15; tail keeled. 
242. G. atkinsii Bean. Slender; V. long. Head 31; depth 5. 
D. I, I, 11. A.I, 8 L. 14. 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; opercles striate ; rugose plates at base 
of spines; spines serrate. Head 33; depth 44. D.II-I,13. A. 
J, 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: wéArn, 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. Il], 1,11. A. 1,8 L. 2. 
N. J. to Labrador ; abundant along coast. (Lat., four-spined.) 
OrpER 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 (Ophiocephalide) wanting. (Lat., 
