334 LAKE SUPERIOR. 



size, those of the upper maxillaries being the smallest and the most 

 curved. The teeth of the vomer are of medium size, between those 

 just mentioned, and somewhat more curved at their summit ; there 

 is a row of them on the hinder semicircular margin of the chevron, 

 then another row on the middle part of the body of this bone. On 

 the tongue the teeth are disposed in a pair of lateral rows ; they are 

 as large as on the palatines, and are the most curved of all. 



The small ossicles disposed in rows along the inner margin of the 

 branchial arches are slightly convex within, and finely denticulate 

 on the outer margin of the curve. On the hinder margin of the 

 lingual bone, at the symphysis of the three first branchial arches, 

 there is a small, narrow and elongated shield with card-like teeth. 

 A similar, but triangular shield is contiguous to the lower pharyn- 

 geal. Finally, a third shield is applied to the side of the upper 

 pharyngeal. 



The eyes are circular and of medium size. Their diameter is con- 

 tained six and a half times in the length of the head, about one 

 diameter and a half from the end of the snout to the anterior margin 

 of the orbit, and four diameters from the posterior margin. The 

 suborbital is composed of five pieces, which form an uninterrupted 

 chain from the margin of the skull to the front of the nostrils. The 

 first is subtriangular, the summit of the triangle being turned towards 

 the side of the eye. The form of the second is an elongated 

 square of which the greatest diameter is in the direction of the length 

 of the body. The third is more irregular, approaching sometimes to 

 the form of a protracted lozenge in the direction of the length of the 

 fish : it borders the lower and hinder outline of the eye. The fourth 

 is elongated, almost straight, very narrow, and has at its surface a 

 row of pores ; it attains the anterior line of the eye. Finally, the 

 fifth is equally perforated, and of a very irregular form ; it protects 

 the lower margin of the nostrils and rests upon the intermaxillary. 

 At the anterior and upper margin of the eye is a small superciliary 

 bone. 



The openings of the nostrils are apparently equal, and near each 

 other, the hinder being somewhat higher ; they are situated at the 

 height of the eye, and nearer to this latter than to the end of 

 the snout ; they are protected by two very thin ossicles. 



