ZOANTHARIA 



55 



I have given the diagnosis of Haddon and Shackleton, which seems to me good, and have 

 added the information, for the Genus Gerardia, that a true cylindric horny skeleton is wanting. I have 

 placed this however in brackets, as I consider further examination of the Gerardia skeleton desirable, 

 in order to ascertain how much of the skeleton actually belongs to the polyp, a determination that 

 can hardly be made without fresh or at least well-preserved material. Though I consider the cylindric, 

 connecting tissue of horn between the branches of the skeleton as being secreted by the polyps them- 

 selves, it is not quite excluded, that the other part of the skeleton belongs to another Authozoon, — 

 a condition undoubtedly existing as regards the basal part of the branched skeleton (cf. Lacaze- 

 Duthiers 1864). If it should be the case, that only the peripheral branches of the so-called Gerardia 

 skeleton have been secreted by the Zoanthid, the genus Gerardia approaches still more to the genus 

 Parazoanthus and comes so near' to this, that the question is, whether the two genera could not be 

 thrown together, especially as the inner structure of the Gerardia polyp agrees completely with that 

 of the Parazoanthus polyp even in such details as the presence of a well-developed encircling sinus. 

 In this case the only difference would lie in the skeleton, certain parts of which are tube-shaped in 

 Gerardia, while in Parazoanthus it is only present as a thin flat layer under the ccenenchyme, a 

 difference which is not essential but gradual and certainly is only dependent on the somewhat unequal 

 growth of the colonies. According to the rule of priority the genus name Gerardia would in such a 

 case have to be changed to Parazoanthus — an alteration which cannot be made, however, until the 

 question of the Gerardia skeleton has been definitely settled. Haddon has for the rest already in 

 1898 p. 408 expressed some doubt as to whether the skeleton in Gerardia was actually secreted by the 

 polyps themselves, though without making any further investigation into the matter himself. 



The Parazoanthus species described here are two in number, one of which has already (1889) 

 been described in detail by Haddon and Shackleton, the other is new, named P. Haddoni. Further, 

 I give here some supplementary details regarding the anatomy of P. dixoni Hadd. & Shackl. 



No species of Parazoanthus were dredged by the Ingolf Expedition. 



Synopsis of the Parazoanthus species described here. 



A. Capitular region in the contracted state not or very little swollen. Number of mesenteries 

 36 — 46 P. haddoni. 



B. Capitular region in the contracted state swollen. Number of mesenteries 36 — 38.. P. anguicomus. 



Parazoanthus haddoni n. sp. 



PI. 1, figs. 9— 11. PI. 7, fig. 5. 



Jutland Reef 100—200 fm. G. Pettersson 1881 R. M. 



Jsederen 100 — 170 fm. Tob. Andersson & Westergreu 1877 R. M. 



N. W. of Egersund 100 fm. N. Ols son & M. Udds trom R. M. 



Haugesund and Bergen in S. E. 15 — 21 miles from land 100—170 fm. 01. Johansson R. M. 



Stora Fiskebanken, Bergen in S. E. 100—180 fm. T. Andersson R. M. 



