STRUCTURE AND DEVELOPMENT OP LOXOSOMA. 311 
Entoprocta is not in reality direct. The larva, it is true, 
possesses many organs which have their homologues in the 
adult ; but I have already explained my reasons for believing 
that it does not itself become mature, and that the permanent 
individuals are produced indirectly by budding. Lankester’s 
theory affords no explanation of the occurrence of the dorsal 
organ, a structure which is entirely confined to the larva. 
Hatschek (17) has exemplified by means of two diagrams 
(p. 106) the homologies between a Pedicellina larva and that 
of an Annelid; he points out that the only difficulty in the 
comparison is the fact that the “ Scheitelplatte” of the former 
has never been identified, although he suggests that this 
structure may be represented by the sucker. His diagram is, 
as I believe, perfectly correct in most of its essential features : — 
in the identification of the surfaces, in the relations of the 
parts of the alimentary canal, in the position of the ciliated 
ring, of the head-kidney, of the subcesophageal ganglion, and 
of the pole-cells of the mesoblast. The only characters in the 
diagram to which I take exception are (i) the identification of 
the sucker instead of the dorsal organ, as the “Scheitelplatte,” 
or brain; and (ii) the opening of the nephridium into the body 
cavity by a ciliated funnel (which Hatschek supposed to be 
also the case in the Polygordius larva). 
Leaving entirely out of consideration the ciliated ring, the 
sucker or foot-gland, and the epistome, all of them structures 
whose homologies are uncertain, the Entoprocta, adult and 
larval, remain essentially modified Trochospheres. The 
existence of paired nephridia, corresponding to the head-kidney 
of Annelid larvae, their inner ends situated in the primary 
body cavity, and their external apertures in front of the 
suboesophageal ganglion, seems to me of especial importance 
in the consideration of this view. The absence of anything 
corresponding to a ciliated funnel, opening into a secondary 
body cavity, is again of importance. The identity of the gut- 
flexure of the Entoprocta with that of Trochospheres has 
not been disproved by Caldwell, who has failed to bring 
forward a single argument against the ordinarily received view 
VOL. XXV. NEW SER. 
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