494. E. A. MINCHIN. 
DESCRIPTION OF PLATE XXIX, 
Illustrating Mr. E. A. Minchin’s paper on “ The Oscula and 
Anatomy of Leucosolenia clathrus, O. 8.” 
PLATE XXIX. 
All the sections of the sphincter have been drawn so that the inner 
(gastral) face of the sphincter looks towards the south, the outer face towards 
the north side of the plate. 
The following letters are for all the figures. 
ect. Ectoderm. exd. Endoderm. a. m. Amcboid mesoderm-cell. mes. Jelly 
(mesoglea) containing spicules. s. The muscular sphincter of the osculum. 
Fic. 1.—Two oscula from a large colony, preserved fresh from the sea in 
70 per cent. alcohol, in profile view. One of them (a) is widely open, the 
other (4) half closed. Natural size. 
Fic. 2.—Three more oscula from the same colony viewed from above. 
Natural size. 
Fig. 2 a.—The osculum of Fig. 2 viewed as a transparent object, magnified 
about three diameters. It is very slightly contracted. 
Fig. 3.—A closed osculum. Natural size. 
Fic. 4.—A small colony with three oscula, magnified five diameters. 
Fic. 5.—A piece of a colony in a very retracted condition, the Clath- 
rina clathrus of Oscar Schmidt, the Ascetta clathrina of Haeckel. 
Fies. 6 a, 6, c, d.—Four sections from a series through one of the oscula 
of the colony represented in Fig. 4: 6a, a section near the middle of the 
series; 64, the next section after 6a; 6c, the next section but one after 6 2; 
6 d, the thirteenth section after 6a. Magnified 350 times. Osmic half per 
cent., picro-carmine, hematoxylin. 
Fics. 7 a and b.—Two sections from a series through a large expanded 
osculum like those in Figs. 1 and 2: 7a, a median section; 7 4, a thick tan- 
gential section. x 3830. Abs. subl., borax carmine, hematoxylin. 
Fic. 8.—A median (transverse) section of the sphincter of another large 
open osculum. Osmic half per cent., picro-carmine, hematoxylin. x 330. 
Figs. 9 a, b, c.—Sections from a series through the closed osculum in Fig. 
38: 9a@ and c, tangential section; 9 c, a detached muscle-cell. Abs. subl., 
borax carmine, hematoxylin. x 330. (In one place the section 9 a is 
slightly broken.) 
