REPORT ON THE ACTINIARIA. 45 



Forumiiiifenil and Radiulariau skeletons, and finally, numerous Sponge -spicules of 

 various kinds. In the coenenchyme between the polyps, the accretions are present only 

 in small quantity, and fill here simple scattered cavities, which may be recognised after 

 decalcification as wide lacunae. The rest of the coenenchyme is soft ; and in its 

 homogeneous matrix we meet with large canals, lined by pigmented epithelium and 

 traversing the coenenchyme in every direction ; they are especially numerous in the 

 lower ccenenchymatous investment, which consequently presents a reticulate spongy 

 texture. As appears from longitudinal sections, these canals are direct continuations 

 of the coelenteron from the base of the polyp outwards, and extend from this point 

 upwards through the whole of the coenenchyme ; they may consequently be homologised 

 with the endodermal connecting tubes to be found in all Zoanthidse. The mesoglcea of 

 the coenenchyme exhibits also numerous roundish cell-islets lined by epithelium, in which 

 we may pei'ceive the origin of such ectodermal cell-heaps as have been described for 

 Epizoanthus. The whole of the endodermal epithelium is pigmented by dark granules, 

 as are also the large endodermal connecting-tubes. On the other hand, the roundish 

 cell-aggregations just mentioned are free from pigment granules ; this difference of 

 condition affords an indirect proof that the latter are by no means of endodermal 

 origin, but are purely ectodermal structures. Finally, the soft coenenchyme exhibits 

 fine nucleated fibres starting from the endoderm, and, as is usual, numerous mesoglceal 

 cells provided with fine processes. 



" The main bulk of the whole colony is to be regarded as coenenchyme ; the 

 individual polyps consist merely of a mesoglceal cylinder lined internally by endoderm, 

 of moderate thickness and homogeneous consistence. The supporting lamina of the 

 mesenteries is of similarly weak development. Below, the latter enclose a canal filled 

 \\'ith cells, which in the case of the macromesenteries is frequently divided up by cross 

 anastomoses. The muscle-pennons are well developed, and appear, especially in the 

 larger mesenteries, as branching processes, which extend over a wide stretch of the 

 mesentery. Nothing of interest can be said about the mesenterial filaments. In none 

 of the specimens investigated could I find generative organs. The stomatodaeum is 

 pear-shaped in section, with a well-marked siphonogl}'phe." 



The sphincter is mesodermal, simple, and only slightly developed. It begins early, 

 as a narrow strip, in that part of the body-wall which is drawn horizontally inwards, 

 and extends without any thickening to the edge of the invaginated part. The number 

 of the mesenteries, which are arranged on the microtype, varied in five individuals 

 between thirty-four and forty. 



Corticifera tuberculosa* Klunzinger (PI. I. fig. 5). 



Individuals closely appressed together and flattened polygonally, generally separated 

 by a deep furrow, and of very dissimilar sizes, so that the surface of the contracted 



