The Latero-Sensory Canals and Related Bones in Fishes. 469 



immediately behind the e^^e by a short section, "Z^;", said to be inner- 

 vated by the supratemporal branch of the nervus lineae lateralis vagi. 

 This section of the main infraorbital line seems certainly to corres- 

 pond to the so-called temporal canal of Batrachus, that is to the 

 glossopharyngeal section of the canal in Amia. From its hind end a 

 dorsal head line runs forward and mesially, and is directly continuous 

 with the supraorbital line at its hind end. A second dorsal head 

 line arises from the middle part of the temporal line, and running 

 almost directly mesially joins the posterior head line at its antero- 

 mesial end, where it also becomes directly continuous with the supra- 

 orbital canal. Herrick homologizes the posterior one of these two 

 lines with the supratemporal commissure and posterior pit-line 

 together, of Amia, and the anterior line with the middle head line of 

 Amia; conclusions with which I fully agree. 



The supraorbital line begins anteriorly at a point on the anterior 

 commissure of the infraorbital line, and from there iiins backward, 

 in a wavy line, directly into the antero-mesial end of the supra- 

 temporal line. That the homologues of the otic organs of other 

 fishes can be included in this line, as suggested by Herrick, seems 

 to me, as already stated, quite impossible. 



The preoperculo-mandibular line begins at the middle point of 

 the temporal line, directly opposite the lateral end of the middle 

 dorsal head line. It runs at first almost directly downward, crosses 

 the hind end of the maxillary part of the infraorbital line, and at 

 an equal distance beloAV that line turns rather sharply forward and 

 extends onto the mandible. Â cross line connects the hind end of 

 its mandibular portion with the maxillary line, this cross line evidently 

 corresponding to one or both of the two lines described by me, in 

 Amia, as the mandibular line and vertical cheek line of pit organs. 

 Two other lines, "f7/c" and "e/i", extend backward from the vertical 

 portion of the preoperculo-mandibular line, one of which, probably 

 the dorsal one "cZ^", may be, as Herrick suggests, the homologue of 

 the hyomandibular canal of Selachians. This line would then also 

 be the homologue of the horizontal cheek line of my descriptions of 

 Amia, notwithstanding that it lies posterior to the preopercular canal. 



