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SIDNEY F. HARMER. 
larvse alive there was not the slighest indication of the loss of 
any of the larval characters or of the approximation, in a single 
feature, to the adult condition. The (probable) fact that the 
larva does not become adult throws some light on the absence 
of the brain in the stalked Loxosoma, since we may assume 
that this organ has been inherited by the larva from a brain- 
possessing ancestor, but has been transmitted to none of the 
individuals produced by budding, and whose development 
cannot be regarded to any great extent as a recapitulation of 
the phylogeny of the Entoprocta. 
In experimenting with the larvse of L. Tethyse and Pedi- 
cellina I have completely failed to obtain any indications of 
the processes of the metamorphosis. This is especially striking, 
since on one occasion larvse of the former were kept alive for 
as much as eight days after they were hatched ; at the end of 
this time they were still free-swimming, and, externally at any 
rate, showed no obvious indications of buds. 
Part 4. — On the Affinities of the Polyzoa. 
The embryology of Dentalium has recently been inves- 
tigated in considerable detail by Kowalevsky (36) ; the agree- 
ment between this description and my own observations on 
Loxosoma is very striking, especially with reference to the 
nervous system. The alimentary canal of Kowalevsky’s larva 
possesses the characteristic Trochosphere bend, whilst the 
mesoblast develops from a pair of pole-cells in the neighbour- 
hood of the blastopore. The shell-gland appears dorsally at an 
early period (whilst the embryo is still a gastrula), and has 
at a certain stage the form of an involuted sac, whose similarity 
in Molluscs in general to the foot-gland of Loxosoma has 
already been pointed out by Lankester (8). In the anterior 
region of the embryo, in the middle of the velar area, originates 
a pair of separate epiblastic invaginations, the “sincipital 
tubes ” of Kowalevsky. These tubes grow backwards into the 
praeoral lobe for a considerable distance, ending blindly one on 
