•548 
EDWIN S. GOODRICH. 
make in this paper is that there is direct evidence of the 
existence of two such “proboscis pores” opening 
into the hypophysis of the Craniate Vertebrates. 
If the evidence be accepted it will, naturally, greatly 
strengthen the theory that the hypophysis and the wheel- 
organ are homologous structures. 
Chiarugi, in 1898 ( 3 ), was, I believe, the first to mention a 
•connection between the preman dibular somites and the hypo- 
phj^sis in Torpedo. Since then Dohrn has carefully described 
this connection in embryos of Torpedo ocellata and mar- 
morata, and of Raja batis ( 4 ). It is a transient structure, 
but when best developed consists of a tubular extension of 
the premandibular somite passing downwards to the posterior 
wall of the hypophysis, and placing the premandibular cavity 
in communication with the lumen of the hypophysis (Text-fig. 
3b). Just as in Balanoglossus, an Echinoderm, or Amphioxus, 
the anterior coelomic sac grows towards and fuses with the 
ectoderm to form the “proboscis” or “water” pore, so in the 
Elasmobranch this tube grows out of the premandibular 
somite and fuses with the hypophysial iugrowth. There may 
be a right and a left tube, but — a significant fact — the left is 
usually better developed and persists longer than the right. 
In Text-fig. 2 a reconstruction is given from a series of 
sections of Torpedo kindly lent to me by Prof. J. P. Hill, in 
which Miss Fraser found the tube. In this case it appears to 
be developed on the right side only. PL 28, fig. 15, shows, 
on a larger scale, the opening into the cavity of the hypo- 
physis. 
Similar structures have been described in the Reptilia. 
Already in 1888 Ostroumoff ( 12 ) mentioned a paired con- 
nection between the premandibular somites and the hypo- 
physis in Phrynocephalus, and the same structure has been 
independently described in detail in the embryo of Gfon- 
gylus ocellatus by Salvi (12a). 
Want of material has prevented my confirming the obser- 
vations of these authors, but, in the 3-day embryo of the 
duck, I find the premandibular somites intimately connected 
