272 M. K. F. Kessler on a remarkable 



specimens it is greater than the distance from the opening of 

 the month. 



At the hinder end of the snout, opposite its lateral hooks, 

 there is the transverse mouth, placed in a separate transverse 

 cavity. The breadth of the mouth is equal to about half that 

 of the whole snout. Both lips, the upper and lower, are divided 

 in the middle by a notch into two curved halves. In front 

 and on the sides the mouth is surrounded by a tubercular 

 fleshy pad ; but in the lower lip there is in the middle a wide 

 interspace between the two halves of this pad. Interiorly both 

 lips are furnished with two rows of small soft warts ; the 

 palate and the tongue are also supplied with similar warts 

 placed in more or less regular transverse rows. Moreover 

 there are also three transverse folds on the palate (Scaphi- 

 rhynchus Rajinesquii has four folds in the palate), of which 

 the front one is curved towards the front, and the posterior 

 backwards. 



The eyes, which are almost opposite to the front, margin of 

 the cavity of the mouth, are exceedingly small, so that their 

 diameter (not exceeding 2 millimetres) is contained not less 

 than fifteen times in the breadth of the interspace between 

 them. In front of them there are the two nasal openings. 

 The upper nasal openings have an oval form, and their diameter 

 is half that of the cleft of the lower. Each of the lower nasal 

 openings is provided from the front side with a tolerably 

 broad skinny flap. The two nasal openings of each side are 

 more approximate to each other with their hinder parts, which 

 are directed obliquely towards the upperside of the head. 



The gill-cavity is considerably shorter and the gill-openings 

 are slightly shorter than those of Scaphirhynchus Rajinesquii, 

 Each of the gill-covers is composed of two bony pieces : the 

 upper one, which is the larger, reaching almost to the gill- 

 opening, is rather rough, sometimes provided with a longitu- 

 dinal central ridge ; the other (lower) one is smaller and almost 

 completely smooth (comparatively larger than that of Scaphi- 

 rhynchus Rajinesquii). The interspace which divides at the 

 throat the two gill-openings is a little wider than that in the 

 American species, and is not less than one half of the transverse 

 diameter of the mouth. 



Two bony lamina? (suprascapular^ and scapulary) border 

 the upper part of the gill-opening. The former has an irregular 

 square form, and is a little larger than the latter, which is 

 almost triangular. Both of these laminae are rough, but not 

 provided with projecting teeth as in Scaphirhynchus Rajinesquii. 

 The two clavicles meet in the central line, and form one broad 

 transverse shield, with two anterior lateral excisions corre- 



