THE LATERAL CANAL SYSTEMS!. 357 



fusiform, thougli still to some extent translucent. Immediately on passing 

 from the fusiform into these masses the nervules dissect into a multitude of 

 very fine branclilets, so fine and so numerous indeed that the masses, on 

 Leucicorus and Mixonus, appear to be quite filled with them. Different 

 genera exhibit few or none of the nervules outside of the fusiform or even, 

 in many, outside of the centrum. Immediately on passing from the fusiform 

 mass into the outer masses, in the genera just mentioned, the nervules divide 

 into finer threads, but on nearing the opposite edges they again unite to 

 form larger branches some of which pass inward to meet nerves going to the 

 brain and others of which accompany the minute connecting thread to enter 

 similar masses in the next organs. Toward the left hand end of fig. 2 

 of Plate XXXIX. oelow the pectoral fin of fig. 1 of the same plate, an 

 attempt is made to depict both the inner nerve, supplying the branches for 

 the centrum, and the outer, gathering up some of the nervules and complet- 

 ing the circuit. Between the two disks drawn in this figure the branclilets 

 have not joined into a single nerve, but they traverse the distance as dis- 

 tinct nervules which branch again on reaching the next organ. As may be 

 seen from this figure there is much difference in the conditions of the nerves 

 between the organs of various directly connected jjairs ; sometimes the ner- 

 vules are numerous, but in the nearest interspace again they may be very 

 few. 



Generally the cephalic organs of the lateral system receive their nerves 

 from the trigeminal and the facial groups, and to a less extent from the 

 glossopharyngeal, and those of the body depend upon the vagus. Within 

 certain limits the main features of the innervation are similar in the differ- 

 ent families noted below, but beyond these limits among the details there 

 are considerable divergences. This is shown by comparison of the nerves 

 of individuals of the same species, Bassozetus nasus, in figs. 1 and 3 of Plate 

 LXXVIII. On figs. 1 and 2 of this plate the nerve has been traced back 

 from each disk to the brain. These figures give an approximate idea of the 

 condition, in all of the main features, in all of the teleosts here dwelt with. 

 By comparison with Amia calva it will be seen that there is a rather close 

 correspondence in the principal features of the innervation. A feature of 

 special interest in a contrast with these figures is the fact that Amia exhibits 

 an arrangement of the system that in respect to aural and supraorbital 

 branches of the cranial canal is intermediate between that of the Scorptenoid, 

 or the Cottoid, of Plate LXXI. fig. 1, or figs. 2 and 3, on which the aural 



