246 EDWARD PHELPS ALLIS, JR. 
anterior to the tip of the notochord. The pituitary body still 
lies between the hind ends of the trabeculae, in the so-called 
pituitary fossa, but the infundibulum now lies dorsal to the 
anterior end of the notochord. The space between the anterior 
ends of the parachordals is now called the interparachordal 
fossa, and this and the pituitary fossa are not only continuous 
with each other in these early stages of development, but are 
considered to continue so to be even in the adult. As the term 
fossa is probably here employed strictly in the sense of fenestra, 
these two so-called fossae will hereafter be referred to as the 
fenestrae interparachordalis and hypophyseos. 
In the third and fourth stages considered by Swinnerton 
(embryos 6.6 to 25-mm. in length) it is said that the intra- 
cranial notochord has undergone no further change beyond 
a slight increase in absolute length, and further, that it under- 
goes no actual suppression or reduction even in later stages of 
development. It is also said that: ‘‘The interparachordal 
fossa has been carried some distance in front of the notochord; 
and the parachordals themselves have united across the inter- 
vening space and across the end of the notochord in such a way 
that this projects below, but close against the basis cranii.”’ 
A transverse plate of parachordal cartilage is thus formed, and 
a median sagittal section through it in a 14-mm. specimen is 
shown in one of the figures given (I. c., fig. 38, pl. 30.). The 
parasphenoid is shown lying slightly below the parachordal 
plate, and the hind end of the musculus rectus externus is in- 
serted on the dorsal surface of the parasphenoid beneath the 
anterior edge of the plate. Somewhat anterior to this point, 
a process of bone is shown projecting dorso-anteriorly from 
the dorsal surface of the parasphenoid, and it is called the me- 
dian process of that bone. In the space between this process 
and the anterior edge of the plate of parachordal cartilage, a 
section of the basal portion of the brain is shown, and, although 
not index lettered, it must represent the pituitary body and in- 
fundibulum of the earlier stages, the infundibulum here slightly 
differentiated as the saccus vasculosus. In a sagittal section 
through this same region of the adult (J. c., fig. 37), the rectus 
