THE MOEMTRIDiE, NOTOPTERID^, AND HTODONTIDiE. 199 



The nasal (No. 3) is narrow and hook-shaped, and semitubular, 

 The suborbital series is constituted by a chain of 9 to 12 bones, 

 which run nearly in a straight line from the back of the pre- 

 maxilhi to the front of the squamosal. The jfirst of these is an 

 oval plate of bone, the size and shape of which are better 

 represented in Hyrtl's figure than in Erdl's ; but the others 

 are merely tubes of bone conveying the cutaneous sensory 

 organ. 



The two premaxillse are rigidly united by an interlocking 

 suture. Each has about seven teeth. The maxillae (No. 2) are 

 curved rods of bone, without teeth ; they are widely separated 

 one from the other, they are attached by fibrous tissue to the 

 posterior ends of the premaxillae, and are not connected with the 

 cranium in any way. 



The two dentaries are not fused at the symphysis ; each bears 

 13 or 14 teeth (see fig. 11), those at the front square-ended *, 

 like the premaxillary teeth, those behind bluntly pointed. The 

 teeth are minutely serrated along the edges. The articular facet 

 for the reception of the head of the quadrate is formed by two 

 bones. The upper one (No. 26 of Erdl's lower figures) is 

 obviously the endosteal articular, while the bone (No. 25) that 

 forms the other half of the facet represents the angular bone 

 fused with the ectosteal articular. There is a well-developed 

 sesamoid articular (No. 27), suturally united with the antero- 

 superior edge of the endosteal articular (see fig. 11). 



The subopercular (No. 30) is relatively small, but it is not 

 entirely concealed by the opercular bone ; it agrees with that of 

 other Mormyroids, however, in terminating in a point posteriorly. 

 The interopercular is large and long, and is concealed by the 

 preopercular. The horizontal limb of the preopercular is nearly 

 twice as long as the upright limb : it is represented as too short 

 by Erdl (No. 28, lower figures). 



Only four brancliiostegal rays are present on each side. Of 

 these, the first is attached to the ceratohyal, the next two to the 

 epihyal, and the last, which is the shortest, lies along the ventral 

 edge of the interopercular, to which its anterior portion is 

 attached by fibrous tissue. Hyrtl {I. c. p. 16) states that his 

 specimen had seven branchiostegal rays on the right side and 

 six on the left ; but Erdl (I. c. p. 229), Duvernoy (Ann. Sci. Nat. 



* The curious chisel-edge of these teeth is not the eifect of wear, for the 

 reserve teeth, yet uncut, present the same feature. 



