ACTINIARIA 



dinal furrows, corresponding to the insertions of the mesenteries, are rather distinct on the scapus. The 

 capitulum is smooth, transparent, without a cuticle and with distinct longitudinal furrows where the mesen- 

 teries insert. The tentacles are badly preserved and stick together, conical, on the larger specimen very 

 extended lengthwise (PI. i, fig. 37) ; 16 in number. The oral disc and the actinopharynx are very macerated. 



Anatomical description: The distal parts of the animal are very badly preserved, so that I cannot 

 give any exact description of the structure of the actinopharynx, tentacles or mesenteries of these parts. 

 The ectoderm of the scapus is, in comparison with the mesogloea, very thin, especially in the proximal parts; 

 gradually the ectoderm increases in thickness towards the distal end. Outside the ectoderm there is a very 

 characteristic layer which reaches a considerable thickness, especially in the proximal body-end (textfigs. 

 68, 69 a). In these places this layer is many times thicker than the ectoderm and sometimes almost as thick 

 as the mesogloea from which it only differs a little in structure. While in the homogeneous ground-substance 

 of the mesogloea we rather commonly find fibrillae, but only rarely cells the part of the mesogloea turned 

 to the endoderm is stained more intensely with borax-carmin and haematoxylin than the outer part which 

 remains almost unstained the layer outside the ectoderm is more homogeneous, though fibrillae and cells 

 also here exceptionally appear, and is only weakly stained with the above-mentioned colouring matter. This 

 layer outside the ectoderm much recalls the so-called sub-cuticle of the Zoantharia, and this likeness is still 

 more conspicuous, in as mush as a thin, brownish cuticle, to which extraneous bodies are sticking, occurs 

 outside the homogeneous layer in Isoedwardsia as well as in Zoantharia, thus forming the outside of the surface 

 of the body. Towards the distal part of the scapus this "sub-cuticular" layer is thinner and does not in its 

 most distal part attain the thickness of the ectoderm. 



The nemathybomes are of about the same structure as in Edwardsia (textfigs. 68, 69 ne) ; they con- 

 tain numerous, rounded, somewhat irregular bodies, surrounded, as it seems, by a refractive, thick mem- 

 brane. The nematocysts () which in the scapus appear only in the nemathybomes and attein a size of 50 

 60 x 4 5 (t, are sometimes a little curved, with the basal part to the spiral thread a little translucent. 

 On the reproduced sections, especially on the textfigure 69, they are obliquely sectioned. The ectoderm of 

 the capitulum is higher than that of the scapus and on one specimen sticking to the tentacles. The ectoderm 

 of the tentacles contains numerous, thick-walled nematocysts (their size 31 36 x 3 fi). The spirocysts of 

 the tentacles are of variable length, the longest about as long as the nematocysts in the same part, but about 

 twice as broad. The nematocysts of the actinopharynx are numerous, 41 46 ;t long and 3 4 p broad. The 

 longitudinal muscle-pennons are in the reproductive region, in transverse-sections, elongated with about 

 30, not densely packed, very often ramificated folds. The larger folds are of ordinary height and almost all 

 of about equal size, the lower folds are sparse (textfig. 70). The parietal muscles are in transverse-sections 

 in the reproductive region oval, with shorter folds in the inner and the outer parts. The folds are often rami- 

 ficated, numerous and spreading apart (textfig. 71). As to the filaments they are not well preserved in the 

 distal part, but in good condition in the reproductive region. It seems as if they are like those of /. medi- 

 terranea, in which the ciliated streaks are discontinuous. Inside the glandular streaks which contain numerous 

 nematocysts, but rare gland-cells, there is, in this species, a well differentiated part, an intermediate streak 

 with rare nematocysts and numerous gland-cells. The reproductive organs were in the one, particularly 

 examined specimen, testes with well developed spermatozoa. 



