REPORT ON THE ACTINIARIA. 23 



inferred that its diameter is here considerably greater than that of the two openings. 

 The radial mesodermal muscle-fibres pass into its walls with a longitudinal trend. 



On the stomatodamm are placed the two siphonoglyphes, which are of a very 

 characteristic appearance, as being more powerfully developed than in any Actinia 

 which I have as yet seen ; each projects over the mouth edge and upwards with 

 two long ear-shaped cones. The groove itself is correspondingly deep and broad, 

 pleated, and of a cartilaginous consistence. Between the two siphonoglyphes run 

 on each side about ten strongly-marked longitudinal ridges, terminating in rounded 

 knobs on the lip. 



In investigating the mesenteries, I could at least prove their arrangement in pairs, 

 but could not convince myself that the Hexactinian symmetry was carried out. Neither 

 by microscopic preparations of a sector, nor by dissection of individual mesenteries, could 

 I arrive at a definite law of arrangement ; this point therefore requires investigation. 



The mesenteries dissected bore no generative organs ; these appeared to me to be 

 confined entirely to one mesentery, and to possess a tubular structure unparalleled in the 

 whole class of Anthozoa, a fact which decided me to choose for the genus the name 

 Aulorchis. Even before dissection it had struck me that at a spot on the edge of the 

 lip, and by a pore specially present for the purpose, was the openiug of a cylindrical 

 organ ; this organ had obviously once been longer, as at its end a fracture was clearly 

 recognisable. By splitting up the opening and the adjacent stomatodseurn, the organ, 

 which I will term in future, for reasons to be mentioned, the genital tube, could be 

 clearly followed into an inter-mesenterial chamber (PI. I. fig. 9). It meets one of the 

 complete mesenteries, lies at this point embedded in the tangle of mesenterial coils, 

 and, as appeared later from sections, ends at the mesentery in a horseshoe-shaped curve. 

 The curved portion was firmly united with the mesentery. Transverse sections yielded 

 further conclusions relative to its structure ; but, unfortunately, owing to bad preserva- 

 tion, no exhaustive account of this is possible. For instance, I have not been so 

 fortunate as to determine how far the structure of the genital tube can be referred to 

 that of the ordinary Aetinian ovary (PL IV. figs. 1-6). 



The genital tube is superficially clothed by epithelium, which is limited exter- 

 nally by a border resembling a cuticle, but perhaps produced only by mucous 

 secretion; then follows the mesogloea with the ova embedded in it; internal to these 

 lies a cavity, more or less spacious according to the mass of the ova. The mesogloea is 

 divided by a narrow granular layer into inner and outer zones, which here and 

 there, by failure of the intermediate layer, join together. The outer zone is narrow, 

 and exhibits what appear to me to be circular muscle -fibres referable to the 

 epithelium, which in longitudinal sections through the organ (fig. 3) resemble narrow 

 laminae placed close together. The state of preservation was inadecpiate for the 

 determination of the histological character of the granular median layer ; in transverse 



