FISHES OF LAKE SUPERIOK. 805 



BOLEOSOMA MACULATUM, Agass. 



Plate IV., fig. 3. 



The general form of this species is slender. The largest specimens 

 which we have studied measured two and three-eighths inches in their 

 whole length. The occiput and the anterior region of the body, before 

 the first dorsal fin, are sensibly depressed. The space which the 

 dorsal fins occupy forms a slightly convex line, sloping backwards 

 and rising again behind the posterior margin of the soft dorsal and 

 before the origin of the caudal. The ventral line is almost straight ; 

 it becomes convex beneath the tail in the same proportion as that of 

 the back is concave. If we add to that a gradual compression of 

 the sides from the front backwards, we shall have for the whole body 

 an oval form, whichsoever be the region upon which we make a 

 transverse section. We shall remark only a gradual decrease of the 

 oval from the head towards the tail. 



The head is short and thick ; it forms just the fifth part of the 

 whole length, measured from the end of the snout, to the posterior 

 margin of the operculum. The snout grows rounded under the form 

 of an arc of a circle, beneath which the upper jaw is fixed horizon- 

 tally. It is about semi-elliptical and slopes over the lower jaw on 

 its whole circumference. The latter, by the third part more 

 narrow towards its symphysis than at the origin of its two 

 branches, appears under the form of an acute angle whose summit 

 would be rounded. The mouth is small and surrounded with a 

 lip, continuous, rounded and uniform on its whole circumference. 

 Card-like teeth, excessively small, visible only with the magnify- 

 ing glass, occupy the margin of the jaws. The vomer also has 

 teeth, but sensibly larger. Upon the pharyngeal bones they become 

 again as slender as upon the jaws. The eyes are large, almost circular, 

 one-eighth of an inch in diameter, situated at the upper margin of the 

 skull, above which they make a regular projection. The distance which 

 separates them from the end of the rostrum is not quite equal to their 

 diameter. The nostrils open in two orifices, both nearer to the orbits 

 than to the end of the rostrum ; the upper orifice is twice as large 

 as the lower ; this latter is nearest the eye. The cheeks are very 



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