94 ALUS. [Vol. II. 



right side of the head, but opposite the sixth myotome on the 

 left side. The first ventral root lay opposite the fourth myo- 

 tome on both sides of the head. In stage B2 the first myotome 

 is said to still exist, and the nerves to have the same relations 

 to the myotomes as in stage B. In stage C the reduction of 

 the anterior myotomes is said to have advanced no further than 

 in the preceding stages. The first two myotomes in this stage 

 are then said to have no related nerves, the third and fourth 

 to have ventral roots related to them, and the fifth to have a 

 complete spinal nerve. Later he says of this same stage, " ver- 

 schwunden sind das vordere Myotom {M\) des Stadiums Bz und 

 die vordere ventrale Wurzel {sp.di)" and "jetzt ist das vor- 

 dere Paar der dorsalen Wurzeln, (welches gegeniiber den Myo- 

 tomen des 6ten Paares, sp.dz, Fig. i, lag), von beiden Seiten 

 gleich entwickelt." That he has here in some way changed 

 the numbering of the myotome seems evident, but it is, never- 

 theless, not at all certain, for although he says in one place 

 that the number of myotomes has changed, he says in another 

 that it has not changed. Whether this uncertainty in the num- 

 bering is perpetuated or not in the descriptions of later stages 

 is difficult to judge. So far as the adult is concerned, the defi- 

 nite statement on page 232, that there are no myotomes ante- 

 rior to the post-occipital one, shows a condition totally different 

 from that found in Amia. The post-occipital myotome is said 

 to be innervated, as it is in Amia, by the first free spinal nerve. 

 In the Characinidae, Sagemehl (No. 5, p. 58) found but one 

 spino-occipital nerve, and he considered it as the homologue 

 of the middle one of the three spino-occipital nerves found by 

 him in Amia ; that is, as the homologue of nerve h of Fiir- 

 bringer's nomenclature. The first nerve posterior to this nerve 

 is said to lie posterior to the stapes, and to innervate the 

 muscle-segment that lies between the first and second vertebrae. 

 The stapes is said to represent the dorsal arch of the first ver- 

 tebrae, and the claustrum to be the homologue of the posterior 

 occipital arch of Amia. As the nerve b in Amia lies anterior 

 to the anterior occipital arch of that fish, there are thus, ac- 

 cording to Sagemehl, two nerves missing in the Characinidae, 

 one of which would be the homologue of the nerve c of Amia, 



