498 MR. H. N. MOSELEY ON THE STRUCTURE OF THE STYLASTERID2E. 
Fig. 4. Tentacle of a gastrozooid of Sporadopora dichotoma, from a sketcli made of 
the animal in the fresh condition. 
K. Elongate knoblike tip of the tentacle thickly beset with nematocysts 
of the smaller form. 
E. Ectoderm. 
Tr. “ Apparent septa.” 
C. Axial cavity of the tentacle. 
Fig. 5. Section transverse to the axis of the zooid of a segment of the body wall of a 
gastrozooid of Sporcidopora dichotoma, taken near the lower region of 
the zooid. 
S. Wall of the sac of the zooid seen in section. 
E. Ectoderm. 
M. Muscular and basement layer showing a series of stout longitudinal 
slips in section. 
L. Layer of transparent endodermal cells, the representatives in this 
region of the larger elongate gastric cells which exist higher up in 
the body cavity. 
E N. Pigmented endoderm cells, such as line the canals of the 
coenosarcal mesliwork. 
Fig. 6. Portion of the muscular layer of the body wall of a gastrozooid of Sporadopora 
dichotoma viewed from its inner surface. The layer is seen to be composed 
of a closely set series of longitudinal narrow muscular slips. The layer is 
crossed by fine transverse striations, the nature of which was not deter- 
mined, no definite circular muscular fibres having been detected in the 
zooids. The striations probably are caused by wrinkles in the basement 
membrane. 
Fig. 7. One of the longitudinal muscular slips of the last figure, much enlarged, to 
show that it is composed of fusiform nucleate closely-packed elements. * 
Fig. 8. These fusiform muscular elements still more magnified. 
Fig. 9. Nematocysts of Sporadopora dichotoma. 
a. Elongate form of nematocyst occurring only in the nematophores and 
surface layer of the ectoderm, and that investing the more super- 
ficial coenosarcal canals. 
a'. The same, with the thread protruded. 
h. Smaller form of nematocyst, abundant in the tentacles of the gastro- 
zooids, ectoderm of the dactylozooids, and other regions. 
//. The same, with the thread protruded. 
c. d. e. Successive stages in the development of the smaller form of 
nematocyst. 
* N.B. — By error in plate, marked + 100 instead of 600. 
