178 ALUS. [Vol. XVIII. 



to any one familiar with the subject, that the sections so inner- 

 vated have been developed from two centers that had much the 

 same measure of independence that belongs to the several groups 

 of organs along the main infraorbital lines of Amia and Scomber. 

 This method of development, from separate centers, seems 

 to be of frequent occurrence in the lateral system, and to give 

 rise, occasionally, to apparent anomalies in the distribution of the 

 canals. Piatt's figures show that it occurs in the hyomandibular 

 line of Nee funis; and the separate innervation of the two parts 

 of the line in that animal is said by her to be due (No. 55, p. 531) 

 to the fact "that the lengthening of the main stem of the hyo- 

 mandibularis has not kept pace with the growth of the sensory 

 line" that gives origin both to the nerve and to the organs of the 

 line. Applied to Chimccra this method of development indicates 

 that the supraorbital canal of that fish has been developed from 

 three secondary centers, two innervated by the ophthalmicus 

 superficialis facialis and one, apparently, by the profundus trigem- 

 ini; and that the section of canal belonging to each center has 

 developed proximally and distally along the line of the canal and 

 fused with the adjoining section or sections to form a single con- 

 tinuous canal, the profundus part of the canal becoming inter- 

 calated between the other two parts. Whether the anterior sec- 

 tion of this canal in ChimcBra has or has not its homologue in 

 some part of the canals of Amia or Scomber is not evident. In 

 Nectnriis it would seem to correspond to the lateral and anterior 

 of the two lines of supraorbital organs described by Piatt. The 

 posterior section corresponds, unquestionably, to a part, or 

 possibly to all, of the supraorbital canal of Amia; and to a 

 part or all of that part of the canal of Scomber that lies pos- 

 terior to its most anterior organ ; plus, in both cases, the an- 

 terior head line of pit organs of the fish. In both Amia and 

 Scomber this anterior head line of pit organs forms a posterior 

 continuation of the supraorbital sensory line, directed toward the 

 supratemporal commissure, and, in Scomber, reaching that com- 

 missure. In larvse of Amia the anterior organ of this pit line was 

 often found partly enclosed in the terminal opening ^f the supra- 

 orbital canal (No. 2, p. 506). In Chimccra the whole pit line 

 must certainly have been' regularly enclosed in that canal, and the 



