LAMPREYS AND FISHES OF INDIANA. 245 



4. Ventrals thoracic or jugular. Dorsal, with few exceptions, having 

 spinous rays three or more in numl^er.* Acanthopteri, p. 248, 



Order 10. HEMIBRANCHII. 



The essential characters of this order are found in their internal anat- 

 omy and need not be given here. In most of the species, which are 

 marine, the bones of the head are prolonged into a long tube, with the 

 mouth at the end ; but in our species the head is rather short. 



Family C4ASTER()STEID,E. 



Body fusiform, with head of moderate length and the caudal peduncle 

 slender. No teeth on vomers or palatines. Skin without scales, but 

 sometimes furnished with oblong bony plates. Dorsal fin preceded by 

 two or more spines not connected by membrane with one another or 

 with the rest of the fin. Anal with one similarly free spine. Ventrals well 

 forward, but still abdominal in position; consisting of one spine and a 

 rudimentary ray. 



A family of small, l)ut vigorous and aggressive fishes. They are stated 

 to do great damage to the young of other species. Most of them build 

 nests for the protection of the eggs, and these nests are defended by the 

 males. 



* Dorsal with seven to eleven spines which diverge from the middle 



line of the back. Pygostens, p. 245. 



*^' Dorsal with five spines, which become erected in the median plane 



of the body. Eucalia, p. 24(5. 



Genus PYGOSTEUS Brevoort. 



Dorsal fin with seven to eleven spines, which, when erect, deviate to 

 right and left of the middle line. Bones bearing the ventral fins united 

 along the middle line, feebly developed, the edges raised. Skin naked. 



Pygosteus pungitius (Linn;). 



Nine-Opined Sticlieback. 



Gasterosteus pungitius, Jordan and Gilljert, 1882, S, 393; Pygosteus pun- 

 gitius, Eigenmann, 1, '89, 235. 



Size small, body long and slender. Caudal peduncle very slender and 

 with a keel on each side. Depth in the length five to six times. Head 

 in length four times, equal to the snout. Mouth quite oblique, of mod- 

 erate size. Dorsal rays IX, I, 9, the anterior spines not erecting in a 

 straight line. Ventral spines more than one-third the length of the head. 

 Anal rays I, 8. Olive above, with darker bars and dots; silvery below. 

 Length about three inches. 



'■'In this group must be included the genus Lota, which has two dorsals, no spines in any 

 of the fins, and the ventrals jugular in position. There is a barbel at the tip of the chin. 



