MATTHAI— RECENT COLONIAL ASTR^ID^ 129 



EXPLANATION OF PLATES* 



PLATES 1—10: ANATOMY OF THE POLYPS 

 Lettering employed. 



A Ig. Alga. alg. nu. Nucleus of alga. ax. Axis of nematocysts II. ax. sh. Sheath of axis of nemato- 

 cysts II. C. ect. Calicoblastic layer of ectoderm. C. nu. Nuclei of calicoblastic ectoderm. Cul. end. 

 Endoderm of column- wall. Col.mg. Mesoglsea of column-wall. d.v. Digestive vacuoles, dir.m. Directive 

 mesentery, ect. Ectoderm, ect. nu. Nuclei of ectoderm, end. Endoderm. end. nu. Nuclei of endoderm. 

 ent. mus. Entocoelic muscle-fibres of mesentery, ent. pi. Entocoelic mesoglseal pleats of mesentery, ent. t. 

 Entocoelic tentacle, ex. pi. Exocoelic mesoglseal pleats of mesentery, ex. mus. Exoccslic muscle-fibres of 

 mesentery, ex. t. Exocoelic tentacle, g.c. Germ -cells, gr. v. Granular vacuole, in. m. Iimer wall of 

 gonad, lot. I. Lateral lobe of mesenterial filament, m. Mesentery, m. end. Mesenterial endoderm. 

 m. f. Mesenterial filament, m. mg. Mesenterial mesoglfea. m. I. Outer limiting membrane of calico- 

 blastic ectoderm, md. I. Median lobe of mesenterial filament, mg. Mesoglsea. muc. v. Mucous vacuole. 

 Wj. Type I nematocyst. n^. Type II nematocyst. n^. Type IIj nematocyst. n^j.. Type 11^ nemato- 

 cyst. n^. Type III nematocyst. n^,. Type III^ nematocyst. n. I. Nervous layer, n. r. Probable stage 

 in the development of nematocyst 11;,. ov. h. Ovoid bodies, ov. nu. Nucleus of ovum. ov. nul. 

 Nucleolus of ovum. py. Pyrenoid of alga. st. end. Stomodseal endoderm. st. mg. Stomodseal mesoglsea. 

 St. r. Ectodermal ridge of stomodseum. sub. h. Sub-terminal tentacular battery of nematocysts. t. end. 

 Endoderm of tentacle, t. mg. Mesoglsea of tentacle, ter. h. Terminal tentacular battery of nematocysts. 

 th. Thread of nematocyst III. th. sh. Sheath of thread of nematocyst III. 



Plate 1. 



Fig. 1. Cyphastrea serailia (Forsk.). (Figs. 1 — 9 all from the same male polyp.) Transverse section 

 through inner wall of edge-zone, showing calicoblastic ectoderm, endoderm with varying nuclei, and 

 algse with granular nuclei and pyrenoids. (102{, iv, Si45.)f x 900. 



Fig. 2. Id. Transverse section through outer wall of edge-zone, showing ectoderm with granular nuclei, 

 some with processes to mesoglsea. (1026 iv, s-^S^.) x 900. 



Fig. 3. Id. Longitudinal section through an exocoelic tentacle to show the histology. (102ft iv, SjS,.) 

 X 433. 



Fig. 4. Id. Transverse section through a primary mesentery and part of the stomodseal wall. Note 

 that the algse occur principally on the exocoelic side of the mesentery, and that the mesentery is 

 contracted in a radial direction. (102^ iv, SiSj.) x 210. 



Fig. 5. Id. Transverse section showing a downward extension of the same ridge and of two lateral 

 extensions of the ectoderm on either side, these lower forming the median and lateral lobes of 

 a mesenterial filament (cp. fig. 6). Semi-diagrammatical. (102i, IV, SiSg.) 



Fig. 6. Id. Transverse section through straight region of the same mesenterial filament. Semi- 

 diagrammatical. (102^ IV, S2I4.) 



Fig. 7. Id. Group of brown vacuoles from the convoluted region of a mesenterial filament towards the 

 base of polyp, surrounding a mass of nucleated protoplasm, each sac with a deeper stained spot 

 in its inner bluntly-pointed end. (102(, iv, S3I3.) x 400. 



* The mesenterial musculature is marked only in tigs. 3, 4, 14 and 27. In all the other sections of the 

 mesenteries it is omitted for the sake of clearness, 

 t This refers to the number of the section. 



SECOND SERIES— ZOOLOGY, VOL. XVII. 17 



