298 
SIDNEY F. HAR5IER. 
brain in Pedicellina, however, is not provided in any known 
species with eyes, this being in all probability a retrogression 
from a more archaic condition. An unpaired ciliated sac, 
described by Hatschek, is connected with the dorsal organ of 
Pedicellina. 
These ciliated sacs of the Entoproctous larvae are not to be 
confused with the primitive cavity of invagination of the brain, 
which loses its lumen during the conversion of its indifferent 
cells into nervous tissue ; they are mere secondary epiblastic 
involutions, either developed for the aeration of the central 
nervous system or having the nature of olfactory organs, as 
suggested by Hatschek (17) for the similar structures in 
Polygordius. 
The eyes of the larva of L. Leptoclini consist of crescentic 
reddish-brown masses of pigment (fig. 55, o), in whose con- 
cavity is imbedded a prominent transparent lens ; the finer 
details of the structure were not made out. 
Eyes are present in most larvae of Loxosoma hitherto 
described, although they appear to be absent in L. pes 
(Schmidt, No. 11). The larva of this species differs to a con- 
siderable extent from that of L. Leptoclini. In Schmidt’s 
figure (Taf. ii, fig. 25) there occurs nothing which can with 
certainty be identified as the dorsal organ, whilst the larva is 
provided with three pairs of bodies of an entirely proble- 
matical 1 nature. The larva of L. Tethyae I find, in external 
features, to be almost exactly like that of L. pes figured by 
Schmidt ; but at present I have not been able to elucidate the 
nature of the three pairs of problematical organs. Eyes are 
absent in the larva of L. Tethyie, although I have succeeded 
in obtaining preparations which demonstrate the existence of 
a brain, especially unmistakeable in the stage represented in 
fig. 62 ( br .). The dorsal organ of the larva of L. Tethyse is, 
however, not nearly so highly developed as that of L. Lepto- 
clini. By comparing the development of the latter with that 
1 Schmidt, in his second paper (20), suggests that one of these pairs may 
constitute the “ Knospenstiicke ” or budding organs of the larva, identical 
with the structures described as such (probably erroneously) in the adult. 
