82 PERCIVAL BAILEY 



hishcr hosprochencn JOiubryonen (H. Sch. 2) dcr hintersto deiu Zwischeii- 

 hirn auliost^ndo Abschnitt der Area chorioidca nach vollkoninKsn glatt 

 iiTui uiist'faltet. 



All of his figures, with the exception of figure 6, appear to be 

 through the diencephalon, back of the velum transversum. 



The development of the paraphysis in the human embryo has 

 never been followed. In fact, its identification is very much in 

 doubt. Francotte ('94) claims to have found it in an embryo of 

 twelve weeks. It is said to be an organ characteristic of all ver- 

 tebrates, but becomes very rudimentary in birds and mammals. 

 Its development has been followed by Dexter ('02) in the com- 

 mon fowl, and it has been described by Selenka ('91) in the 

 opossum. A good review of the literature is given by Warren 

 ('05). 



Of the human embryo, Streeter in Keibel and Mall's Human 

 Embryology says, 



Orally this choroid roof [of the third ventricle] is continued into the 

 telencephalon where it forms a pointed pouch overlapping the lamina 

 terminalis and the contained commissures. . . . The anterior cho- 

 roidal pouch has been homologized with the paraphysis of the lower 

 vertel^rates. 



It should be borne in mind, that in all vertebrates, the para- 

 physis, if present, arises from the roof of the telencephalon just 

 cephalad to the velum transversum. In view of this fact, the 

 structure labelled paraphysis by Goldstein ('03) is obviously 

 not so, since it lies behind a structure called the .velum trans- 

 versum and at the posterior end of the diencephalic roof. 



The epiphysis is a constant organ in the vertebrate series^ 

 (except in the alligator) but probably concerning no other organ 

 has there been so much confusion and misinterpretation. For a 

 review of the literature, reference may be had to Gaupp ('98). 

 The development of the epiphysis "has not been followed com- 

 pletely in the human embryo, and so far as I know, an indication 

 of the division into the two parts, epiphyseal stalk and pineal 

 vesicle, which seems to be so characteristic of many vertebrates, 

 has never been recorded. 



With the recognition of the velum transversum in Cyclostomes 

 by Sterzi (07), the velum has been established as a constant 



