418 G. HERBERT FOWLER. 
those of Dr. von Heider on the “ Rand-platte ” of Cladocora receives an easy 
explanation, if the latter may in some cases be absent. 
In the shells of Dentalium and various Gastropoda tenanted by Phascolion 
strombi, which have been dredged this summer by the Marine Biological 
Association at Plymouth, I have vainly looked for pores corresponding to 
those round the base of Heteropsammia and other corals mentioned on p. 413 ; 
nor can I find mention of such in the account of the Sipunculide by Selenka 
and others in the ‘ Reisen im Archipel der Philippinen.’ I owe, however, to 
Mr. A. E. Shipley a reference to a paper by Théel (‘ K. Svensk. Vet.-Akad. 
Handl.,’ xiv, p. 6), where it is stated that lateral holes do occasionally occur 
in shells so tenanted. 
EXPLANATION OF PLATE XXVIII, 
Illustrating Dr. G. Herbert Fowler’s paper on ‘‘ The Anatomy 
of the Madreporaria: V.” 
c. ec. Cylindrical canal. or. d@. Oral disc. 
cel. Colenteron. | or. @', Invaginated oral dise. 
col. Columella. | p. Palus. 
ech. Hchinulation. | Se. Septum. 
ect. Hctoderm. sph. Sphincter. 
en. Endoderm. | st. Stomodeum. 
h. c. Hemicylindrical canal. te. Tentacle. 
me. Mesogloea. th. Theca. 
| 
| 
mes. Mesentery. | 
Fic. 1. DUNCANIA BARBADENSTS (Pourt.).—View from above of the polyp 
in a retracted condition. That part of the tissues lying on the projecting lip 
of the epitheca is not marked by the septa. The oral disc has been drawn 
inwards by the sphincter muscle, allowing the opening of the stomodeeum into 
the coelenteron to be seen below; this opening is nearly blocked up by the 
pillared columella in the centre. (After a MS. sketch by Professor Moseley.) 
Fic. 2. DUNCANIA BARBADENSIS.—Ideal diagrammatic section in a vertical 
plane. The soft tissues lie entirely within the corallum, of which ep. marks 
the region of epitheca projecting above the level of the septa, and ¢h. the 
region formed of epitheca and true theca; the hard tissues are indicated by 
dotting. The tentacle is seen to lie in a pouch of the oral disc formed by the 
contraction of the sphincter, lying above the stomodzum. 
Fic. 3. DUNCANIA BARBADENSIS.—Diagrammatic section of a pair of 
mesenteries and the associated structures, in the plane indicated by the arrow 
in Fig. 2, to show the relations of the body-layers. (Cf. p. 407, note.) 
