446 Edward Phelps Allis jr., 



of the line, Nos. 9 and 10, lie in tlie squamosal, one immediately 

 posterior to the point of anastomosis with the supraorbital canal, and 

 the other immediately posterior to the point of anastomosis with the 

 preopercular canal; this last organ being innervated by a branch of 

 the postfacial nerve that innervates also the organs of the supra- 

 temporal canal. The 11th. organ lies in the main canal slightly 

 posterior to the point of origin of the supratemporal canal, and the 

 12 th. and 13th. organs in the suprascapular and supraclavicular bones 

 respectively. 



The preoperculo- mandibular canal is fully shown in the figure, 

 and no special description of it is here needed. 



The supratemporal canal is greatly enlarged at its point of 

 origin from the main infraorbital, the latter canal being also here 

 enlarged, so that a rather large sinus is formed which lies in the 

 membranous tissues that cover and close the "äussere Gehöröffnung" 

 of Erdl's descriptions. The supratemporal canal runs antero-mesially 

 across the Gehöröffnung, there lying in a groove on the inner surface 

 of the Gehördeckel, the groove leading on to the inner surface 

 of a process of the Gehördeckel that projects antero-mesially beyond 

 the Gehöröffnung onto the outer surface of the dorsal arm of the 

 squamosal. The squamosal is here slightly grooved to receive the 

 tube, the tube ending blindly slightly beyond the apex of the process. 

 There are two sense organs in the canal, and a short primary tube 

 arises from the canal between them, this tube perforating the Gehör- 

 deckel and then there ending blindly. 



The Gehördeckel of Erdl's descriptions of Gymnarchus, and hence 

 also of his descriptions of Mormyrus, must then certainly be an extra- 

 scapular (supratemporal) bone, and as such Dr. Boulenger writes me 

 that he also considers it; adding that his statement [17, p. 164] re- 

 garding the Mormyridae in general should have been corrected from 

 "supratemporal .... covering the greater part of the parietal bone" 

 to "covering the parietal or squamosal". 



The "äussere Gehöröffnung" of Erdl's descriptions of Gymnarchus 

 is the surface opening, or mouth, of a large pit, the anterior half of 

 which is bounded by the squamosal and petrosal bones and the 



