The Latero-Sensory Canals and Related Bones in Fishes. 407 



middle head line is innervated by a branch of that branch of the 

 glossopharyngeus that innervates the posterior squamosal organ; and 

 the posterior head line is innervated by a branch of that supratemporal 

 branch of the nervus lineae lateralis that innervates the organs of the 

 supratemporal canal. The innervation of the other lines is not here 

 important. 



A latero-sensory organ, innervated by a branch of the ramus 

 oticus, and quite undoubtedly of ectodermal origin, is found in the 

 dorsal end of a diverticulum of the spiracular cleft. 



On the dorsal surface of the chondrocranium there is, on either 

 side of the head, a longitudinal groove covered externally by the 

 extrascapular, the parietal and the dermo-squamosal. The space thus 

 covered was called by Sagemehl the temporal hole, and the groove 

 on the dorsal surface of the chondrocranium has been called the tem- 

 poral groove. It lodges an anterior extension of the anterior segments 

 of the trunk muscles. 



Lepidosteus osseiis. CoUinge [28] has described and figured the 

 lateral canals and canal bones of Lepidosteus, but both his figures 

 and his descriptions are inaccurate. 



The accompanying figure 1 gives a lateral view of the head of a larval 

 Lepidosteus, and figs. 2, 3 and 4 give lateral, dorsal, and ventral views of 

 an adult. The drawing used for fig. 1 has been compiled from un- 

 finished sketches made by Mr. Nomura, in 1887/88, in my Lake 

 Laboratory, Milwaukee, and from a hasty reconstruction made by my- 

 self, at the same time, from serial sections of another larva. Neither 

 the length nor age of either of the larvae was given on the sketches. 

 As the sections of the one, and the specimen used for the drawings 

 of the other, have both unfortunately disappeared, the absolute 

 accuracy of the figure can not be vouched for, but it is certainly 

 practically correct. The drawings used for the three figures of the 

 adult have been recently made in my laboratory here, by Mr. Nomura, 

 and they represent the canals in a rather large fish, the disarticulated 

 skeleton of which, prepared in 1887/88, I still have. The results ob- 

 tained on this skeleton were controlled on a second but quite imper- 

 fect skeleton. 



