266 PROCEEDINGS OF THE CANADIAN INSTITUTE. 



they have also been named." Such a condition does not occur- in 

 Amiurus ; but other accessory protected nerve-hillocks are present, 

 of which I can find no mention in the literature of the subject, 

 unless they prove to be structures similar to those described by 

 Leydig in the pike and burbot. He says of the former : " In addi- 

 tion to those ' lateral organs ' which are present along the principal 

 and accessory lateral lines they are distributed also elsewhere. On 

 the trunk they are arranged in rows transverse to the long axis of 

 the body. Each row may be composed of six to ten hillocks. In 

 such spots the pigment of the skin, only approaches so as to form a 

 sort of boundary line, and the slime cells are likewise absent, so that 

 the row of sense-hillocks has something of an isolated character, 

 although not situated within a furrowed scale." 



" To give approximately the number of transverse rows of sense- 

 hillocks is impossible, as I have not succeeded in recognizing them 

 with the loup on the unwounded skin. Horizontal sections and 

 microscopical investigations will be necessary to determine their 

 number and arrangement." 



" On the skin of the head, e. g., the region of the cheeks, beaker- 

 shaped organs of the usual size ai*e to be found, as well as others 

 which are not inferior in size to the nerve-hillocks of the lateral 

 lines, so that it is indifferent what name we give them." 



"It is worthy of remark that the beaker-shaped organs of the pike 

 and the organs of the lateral line on the trunk agree essentially in 

 their structure." 



Of Lota, Leydig says (p. 39) : " In the head region the pores of the 

 mucous canals are also present, but more numerous, and although for 

 the most part restricted to the course of the mucous canals, they are 

 also to be found in spots far from any mucous canal. The same is 

 the case on the trunk. If all of these points are actually pores of 

 the system of mucous canals, the principal tubes of these must send 

 off long branches in the corium to open in this manner. It is pro- 

 bable, however, that the structures indicated are nothing but large 

 beaker-shaped organs." 



As has been remarked above, Leydig does not sufficiently dis- 

 tinguish in the above passage and elsewhere between 'beaker- 

 shaped organs ' and ' nerve-hillocks.' 



Amiurus possesses certain structures which I am inclined to believe 

 are comparable to the scattered nerve-hillocks described by Leydig 



