20 Paraphysis and the Pineal Region in Necturus Maculatus 
In the crocodilia Voelzkow (39) has described the paraphysis. of 
Crocodilus madagascarensis grand and Caiman niger spix. In the former 
the paraphysis is at first a wide tube which becomes convoluted and much 
longer and narrower. In the latter the paraphysis forms a larger tube 
and the convolutions and tubules are more complicated. In both cases 
the organ reaches its greatest development in embryonic life and retro- 
grades later, though more so in the crocodile. He was unable, however, 
to follow the development in the caiman as far as in the crocodile. 
Owing to the thickenings in the brain wall the organ is crowded some- 
what caudad against the post-velar arch. 
In birds the paraphysis is relatively rudimentary. Burckhardt (3) 
shows the paraphysis in an embryo of the crow as a small diverticulum 
not unlike that of Petromyzon. Dexter (5) worked out in detail the 
development of the organ in the common fowl, and showed that it ap- 
peared at first as a small diverticulum. The walls become much thick- 
ened and in a chicken of 10 days it is a small, oval structure, about 150 p 
in its greatest diameter, with very thick walls (5, Fig. 5). Selenka (34) 
has described the paraphysis in the oppossum, but as far as I am aware 
little is known of the development of the paraphysis in mammals, though 
Francotte (11) has observed it in human embryo of twelve weeks. 
From the cyclostomes to the amphibia the paraphysis shows a steadily 
progressive development, and the various forms through which it passes, 
from the simple diverticulum of Petromyzon to the elaborate gland of 
the urodela, are illustrated in a general way by the stages of its develop- 
ment in Necturus. In the vertebrates above the amphibia the paraphysis 
retrogrades and practically retraces its steps through the reptilia and 
birds to mammals, reaching in the chick essentially the same form in 
which it started in Petromyzon. Its development, therefore, may be 
indicated by a curve, which ascends steadily from the cyclostomes, reaches 
its height in urodela, and descends through the reptilia and birds to 
mammals. 
The epiphysis is present in nearly all vertebrates. It is stated to be 
absent in the alligator (Sorensen, 36 and 37), and in the caiman and 
crocodile (Voelzkow, 39) and in Torpedo (d’Erchia, 7). 
The epiphysis of Necturus as compared with the paraphysis is relatively 
poorly developed and in this respect resembles the epiphysis of other 
urodela (Mrs. Gage, 13). In Diemyctylus Mrs. Gage found that the 
epiphysis was entirely cut off from the brain and that its cavity was 
nearly obliterated. In Ichthyophis (Burckhardt, 1 and 4) the epiphysis 
is a small, pear-shaped organ attached to the brain by a narrow solid 
stalk. Herrick (15) in Menopoma, describes the epiphysis as an irreg- 
