22 ZOOLOGY OF THE FAR EAST. 
third part of the cardiac region. In the Vesicularina, or at any rate in Bowerhankia 
(fig. 2, D), the general structure resembles that found in Hislopia, except that the 
horny lining of the spherical chamber is broken up into a number of sharp teeth ' , 
and that there are no cilia on the narrow ring that separates the spherical chamber 
from the pylorus. 
Thus, in three families, belonging to two different divisions of the suborder, we 
find a chamber lined with chitin in the cardiac region of the alimentary canal. In 
the Hislopiidae and the Vesiculariidae this chamber occupies the same position and 
is probably homologous, though, as we shall see in a moment, it is not analogous. 
In the Victorellidae it differs both in position and in function and seems to be homo- 
logous rather with the proventriculus of the other families than with their spherical 
chamber. If this be so, the spherical chamber of these forms is homologous with the 
narrow muscular part in Vidorella. In Bowerhankia the function of the chamber 
with the horny teeth is that of a true gizzard. It crushes the food. In Hislopia the 
function is rather that of a store-chamber; the chitinous lining has very little 
crushing pow'er and its function is merely to maintain the spherical form of the cham- 
ber in a position of rest, without preventing a change of shape and consequent dimi- 
nution of the lumen in muscular contraction.^ In Victor ella the function of the 
horny region seems to that of retaining hard particles of irregular shqpe which might 
injure the delicate walls of the stomach, the natural food consisting of diatoms with 
a smooth surface.'^ 
In this summary description I have taken the oesophageal valve as a fixed point, 
as seems to be justified by a comparative study of the alimentary canal in different 
groups of Ctenostomata ; but the term oesophagus has been applied in Alcyonidium 
by others not only to that region to which I have confined it, but also to the whole 
of the alimentary canal between the mouth and the stomach proper. The term 
''gizzard" is applicable, in a physiological sense, only to forms like Bowerhankia 
and Crypiozoon, and it is perhaps best not to use it either for the homologous, but 
not analogous, structure in Bowerhankia, or for the superficially similar, but neither 
homologous nor analogous, structure in Vidorella. 
Division ALCYONELLEA. 
Harmer * in his recent report on the Ctenostomata of the ' Siboga ' has revived 
Gray's name Carnosa (1841) for this division, on the ground that Ehrenberg's name 
Halcyonellea (1839) included Phylactolaemata as well as Ctenostomata. 
Family ALCYONIDIIDAE. 
Genus Alcyonidium, Lamx. 
1915. Alcyonidium, Harmer, op. cii., p. 36. 
1 In the anomalous genus Crypiozoon, Dendy, which perhaps belongs to this division, the horny layer takes the 
form of a, pair of stout quadrangular masses. See Dendy, Proc. Roy. Soc. Victoria (n.s.;, I, pp. 1-12, pis. i-iii (1889). 
2 Annandale, Faun. Brit. Ind., Freshw. Sponges, etc., pp. 2ix>-2C2 (1911). 
•■ Id., ibid., p. 197. 4 Siboga-Exp., mon. XXVIIIa, p. 35 (1915). 
