Kingsbury, Brain of Nectmus. i6i 



coele was found, however, as is said by Herrick to be the case. 

 In the just hatched larva the condition was simpler, the epiphy- 

 sis at that stage being a simple hollow vesicle, not communicat- 

 ing even at this early stage with the brain cavity. Two or three 

 myelinic nerve fibres, one each side, were found to pass to the 

 ectal surface of the brain and disappear after turning mesad be- 

 neath the epiphysis. They came from the mesencephal to 

 which they could be traced caudad. This fact is presented 

 without comment, but is interesting and suggestive in connec- 

 tion with what has been written regarding a parietal nerve. 



ParapJiysis, etc. — Three evaginations of the roof of the 

 brain have been recognized, all of which may be present in the 

 same form, viz., (i) the epiphysis between the post- and su- 

 pracommissures ; (2) cephalad of the supracommissure an 

 evagination which has been variously termed zirbel-polster, pol- 

 ster, dorsal sac, and postparaphysis ; (3) the third farther cepha- 

 lad, separated from the second by the velum, and here called 

 paraphysis. An admirable resume of the literature of the sub- 

 ject is given by Sorensen ('94, i) by whom the ierva paraphysis 

 includes the two more cephalic evaginations, which he considers 

 are caused by the division of his paraphysis by the velum into 

 cephalic and caudal portions, the pre- and postparaphysis. He 

 says of these ('94, 2): "The causes for the varied forms found 

 in the paraphysis must, we think, be sought for in the mechan- 

 ics of embryonic growth and development, and, as already re- 

 marked, to call these sac-like projections epiphyses is absurd, as 

 their structure and position prove their plexiform origin." 

 There is entire agreement with the above as regards what has 

 been called '^postparaphysis'' in Amphibia. In the just hatched 

 Nectiirus, the parts lie much nearer together. The walls of the 

 diencephal extend cephalad between the cerebrums quite to the 

 velum and there is not the extent of the tela in this region that 

 there is in the adult. The simple diaplexus arises from the 

 velum. But while there is no indication of an evagination 

 caudad of the velum, the parapJiysis cephalad of It is well de- 

 veloped as a bulblike sac communicating with the brain cavities 

 by a constricted neck. In Amphibia, at least, t\\e preparaphysis 



