37. MESOPKION, 197 



Museum, from the west coast of Africa ; they represent one or two 

 nominal species of Valenciennes (M. goreensis, and probably M. ful- 

 gens) ; the females have a considerably more elevated body than the 

 males. 



•y, B. Adult : male. Eiver Niger. From Mr. Fraser's Collection. 

 €. Adult : female. River Niger. From Mr. Fraser's Collection. 

 ^. Adult : female. Coast of Africa. From the Haslar Collection. 

 T}. Half-grown. Fernando Po. From Mr. Fraser's Collection. 



Skeleton. — The maxillary bone gradually widens from the base to 

 its extremity, and has the posterior margin convex and the anterior 

 concave. The posterior processes of the intermaxillary bones are of 

 moderate length, about two-thirds the length of the bones themselves ; 

 these are armed with a pair of very strong canines, between which 

 are two other pairs of smaller ones ; there is a series of short conical 

 teeth along all the outer margin ; the remainder of the teeth form a 

 villiform band. The mandibulary is furnished with an outer scries 

 of conical teeth ; those standing in front of the jaw and in the middle 

 of the side of the dentary are the largest and canine-Uke ; the villi- 

 form band of mandibulaiy teeth does not extend on the lateral por- 

 tion of the dentary. The vomeiine teeth are arranged in an anchor- 

 shaped \illiform band, which extends backwards to the middle of 

 the bone. The palatine teeth form a broad band, three times as long 

 as broad, which does not extend on the pterygoid. The tui'binal 

 bones are strong, elongate, and being very divergent, they leave 

 between them a triangular groove, to receive the processes of the 

 intemiaxillaries. The anterior portions of the frontal bones also 

 diverge, and leave between them a space, filled up by an elongate 

 portion of the ethmoid, which in this and other species of Mesoprion 

 forms part of the upper surface of the shuU. The space between 

 the orbits is rather narrow and flat, with some grooves and openings 

 of the rudimentary system of mueiferous channels. The portion of 

 the upper surface of the skull, behind the orbits, is distinguished by 

 high crests,, leaving between them very deep longitudinal grooves. 

 The median crest is that of the supraoccipital bone, Avhich, strong, 

 but moderately elevated, slightly bifiu'cates in front, and extends on 

 the frontal bones to above the middle of the orbit. Two other crests 

 arise from the orbit, the inner of which runs (nearly parallel with 

 that of the occipital bone) to the articulation of the superior piece of 

 the suprascapula ; the outer crest descends downwards in a slight 

 curve, and terminates at the junction ofthe suprascajjula, operculum, 

 and prsDoperculum. The groove between the two outer crests is tri- 

 angular, and a large oi:)ening leads into the occipital region. The prae- 

 orbital is large, in'egularly quadrangular, and smooth ; the remainder 

 of the infraorbital bones are narrow, and form the base for a large 

 concave plate reaching into the interior of the orbit. 



The operculum has neither spine nor notch ; the sub- and inter- 

 opcrcidum entire. The limbs of the praeoperculum have a very oblique 

 direction towards each other ; the angle is rounded, and anned with 

 strong spinous teeth ; the posterior limb is minutely serrated in all 



