Stephenson — Certain Actiniaria collected off Ireland. 161 



13-15. Cells from mesogloea of body-wall (at different levels). (Chondro- 

 dactis pulch/ra.) 

 16-20. Cells from tentacle mesogloea. (Actinostola atrostoma.) 



21. Cell-chain from tentacle mesogloea. (Actinermis aurclia.) 



22. Cell from mesogloea of mesentery. (Chondrodactis coccinea.) 



23. Cell from mesogloea of tentacle. (Chondrodactis coccinea.) 



24-26. Three small areas from the body-wall, at different levels, of Chondro- 

 dactis coccinea, showing a little ectoderm and mesogloea (24, 25) or 

 endoderm and mesogloea (26), and the included cells. 



27. Carlgrenia desiderata. A small portion of ectoderm and mesogloea from 



the upper part of the body-wall, showing a battery of thick-walled 

 nematocysts (in black). Oc. 3. Obj. f. 



28. Actinermis aurclia. Small portion of the ciliated lobe of a large mesen- 



terial filament. Oc. 3. Obj. ^. 

 30. Gland-cell from tentacle- ectoderm of Actinermis saginahis. Oc. 3. Obj.^V, 

 29,30«,3L-33. Diagrammatic representations of small portions of the capitu- 



lum of different specimens of Actinaugc richardi. Slightly enlarged- 

 34-37. Exact representations of small portions of the capitulum of several 



specimens of Actinaugc richardi. Slightly enlarged. 

 38. Diagram of relation of tentacles, ridges, &c, in Actinaugc richardi. (See 



description of that species.) 

 39,40. Diagrammatic longitudinal sections of two specimens of A. richardi, 



to show relative proportions of cavity of basal cup and coelenteron- 



cavity, in two different cases. Slightly reduced. 

 41. Chondrodactis coccinea, n. sp., seen from above. Nat. size. 



Plate XVII. 



1. Actinostola atrostoma. Transverse section of a tentacle near its base. 



Very low magnification. 



2. „ „ Exact detail of a small portion of the band of 



longitudinal musculature shown in the T. S. of a 

 tentacle in fig. 1. The whole width of the band 

 is represented, and the letter n is placed in the 

 mesogloea on the endodermal side of it. Oc. 3. 

 Obj. f. 



3. „ „ Detail of part of the outer side of the sphincter, 



about the middle of its length. Oc. 3. Obj. §. 



4. „ „ Diagram showing shape and position of whole 



sphincter, x ca. 3$ diams. 

 6. „ „ Part of a 3rd cycle mesentery. Obj. 1 j. 



R.I.A. PROC, VOL. XXXIV. SECT. B. [I'] 



