ACTINIARIA 



and perforated by numerous apertures, arranged in 12 longitudinal rows (Haddon 1889, p. 337); it may 

 be perfectly involved. The column is rugose in contracted state, in expanded smooth. According to Haddon 

 and Dixon 1885, p. 401) it is furnished "with numerous minute suckers." I have carefully examined spec- 

 imens received from Haddon; they were in certain parts of the body strongly expanded, partly in trans- 

 verse-sections, partly in preparations in toto in glycerine. As far as I can make out there are no "suckers", 

 nor such low elevations as on the column of Eloactis. It seems to me that the "suckers", which nowise deserve 

 this name, are nothing but cell-accumulations containing some more supporting cells than the other parts 

 of the ectoderm. By an examination of the surface of the column, in preparations in toto, it is namely clearly 

 seen that the main part of the mucus-cells form an irregular net-work, between which are distributed some 

 more compact parts of the ectoderm, mainly consisting of supporting cells, but also of scattered mucus-cells. 



The tentacles are 12, arranged in two cycles, the inner tentacles are shorter than the outer ones 

 and issue from the endocoels, while the latter are exocoel-tentacles, an arrangement distinctly appearing 

 in the larvae, but also visible in the adult animal. Thus I cannot agree with Haddon and Dixon that the 

 tentacles are monocyclic. On the other hand, the description of the arrangement of the tentacles given by 

 Faurot (1895) is exact. (Compare also Carlgren 1904). As to their form they are cylindrical, a little atte- 

 nuated towards the apex and of about the same length as the diameter of the body. The oral disc is smooth, 

 flattened and provided with radial furrows corresponding to the insertions of the mesenteries. The mouth 

 is wide, in live animals commonly covered by the conchula. 



The conchula is strongly developed, consisting of three main lobes, one in the directive plane and 

 two lateral ones. From these smaller lobes tentacle-like prominences issue, so that the total number of lobes 

 varies from 6 to 10 (Haddon and Dixon), according to the age of the animal. In the larvae and young spec- 

 imens only the main lobes are developed (compare below!). The other part of the siphonoglyphe is very 

 deep, distinctly differentiated from the other part of the actinopharynx, smooth, not wrinkled, and pro- 

 vided with a very long aboral prolongation which is twice as long as the main part of the actinopharynx. 

 This latter is comparatively short, of about the same length as the diameter of the body, longitudinally 

 sulcated, and in contracted state also with transversal folds. On the side of the aboral prolongation 

 of the siphonoglyphe the actinopharynx is continued as narrow lamellae (compare below!). 



Anatomical description: The anatomy of the adult species is described by Haddon (1889) 

 and Faurot (1890, 1895). The latter (1895, p. 94) gives a more detailed description of the species, with nume- 

 rous figures of sections through different parts of the body. Besides this, Sedgwick 1884, p. 43) has pub- 

 lished some anatomical details of the species. In some respects the anatomy is, however, imperfectly de- 

 scribed. For anatomical examination I have used partly a specimen from Frederikshavn, partly and mainly 

 specimens from Ireland, dredged by Haddon, partly the sections made by Haddon who has placed them 

 at my disposal. 



The ectoderm of the column is ordinarily developed, in the contracted state of the animal thick 

 and furnished with numerous mucus-cells, arranged as I have shown above. Its nematocysts are not numerous, 

 and 12 16 X about 2 ;t in size. The mesogloea is longitudinally and transversally stratiform as in Halcampa, 

 and of ordinary thickness. The endodermal circular muscles are rather well developed, but form no sphincter. 



