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The anterior, or paraphysis, arises either slightly anterior or po- 
sterior to the line which marks the boundary between prosencephalon 
and thalamencephalon. Concerning the fate and function of this organ 
there is much difference of opinion. FRancorre derives from it a 
portion of the future choroid plexus. Hmm believes it to degenerate. 
SELENKA suggests that it may be the rudiment of an ancestral ear, 
while Lrypic finds, instead of a single vesicle, a group of five which 
later comes into such close relation to the epiphysis that SPENCER 
figured both as one structure. 
In view of the existing discord concerning its fate, I trust that 
the following note taken from my manuscript on the development of 
Amblystoma, may serve to elucidate the relation of the structures in 
Urodela. 
The first trace of the ephiphysis is in a 5 mm embryo where 
it shows, in section, as a crescentic evagination in the roof of the 
thalamencephalon. The lateral walls are formed of several layers of 
cells, while the dorsal which comes directly in contact with the super- 
ficial layer of the epiblast is but a single layer. The nuclei undergo 
a marked migration toward the periphery; in this respect the appear- 
ance is strikingly similar to the condition found in the optic vesicles 
which at this time are strongly evaginated. The presence of pigment 
at the inner ends of the cells is also a significant fact. From this 
time, until the formation of the lens in the lateral eyes, the epi- 
physis increases in size, its cavity becomes elliptical and is in wide 
communication with the thalamocoele. 
At the time of the invagination of the lens there appears in the 
posterior portion of the roof of the prosencephalon a second median 
outgrowth which is directly homologous with the paraphysis described 
in Reptillia by SELENnkA. Its walls consist of a single layer of cells 
the outer ends of which are pigmented. 
In a 12 mm larva the paraphysis is much elongated, lateral 
diverticula appear at its distal end while the cavity is obliterated 
proximally in a manner analagous to that which occurs in the epi- 
physis. The changes are more pronounced in a 14 mm larva where 
it has assumed a digitate appearance and bears a striking resemblance 
to the true choroid plexus of the lateral ventricles. 
The two structures in Urodela never come into close relation, as 
in Reptilia, but remain widely separated. 
That the paraphysis is indeed a peculiar organ, very similar in 
development to the epiphysis, is shown not only by SELENKA but 
also by Leypia in his final memoir, where from its exceptional moda 
