ni 



Duva flo ri da. (J. R at hk e.) 



Tab. II, figs. 13 — 21. 



This Alcyonarian, first described by Jens Rathke, under the name of Gorgonia florida, was tåken by Professor M. 

 Vahl, at Moskenæs in Nordland and Loppen in Finmark. Vahl observed and figured the animal in a living state; and it is 

 this drawing Jens Rathke has copied in Zoologia danica. Since then, the species has hardly, we believe, been met with by 

 any naturalist, but has now and again been confounded with other Alcyonarians, which, in certain characteristics, approximate 

 the animal. Rathke regarded it as a Gorgonida, to which genus however it cannot be referred; and hence Ehrenberg has re- 

 ferred it to the genus Nephthya, designating the species Rathkiana, since in the genus Nephthya there was already a species 

 bearing the appellation florida. 



Fortunately, in the Museum of Bergen we have two examples of an Alcyonarian, which, on examination, proved to 

 be the true Gorgonia florida described by Rathke; and, strange enough, one of these specimens is from Moskenæs in Nord- 

 land, the other from Finmark. Agreement with a Gorgonida is quite out of the question ; nor could we, on closer investigation, 

 leave this species in the genus Nephthya, from which it essen tially differs; we have therefore referred it to our new 

 genus Duva. 



Dr. Marenzeller, in his Memoir entitled — «Die Coelenteraten, Echinodermen und Wiirmer der K. K. Oesterreichisch- 

 Ungarischen Nordpol-Expedition,» has described an Alcyonarian belonging to a new genus established by himself under the 

 name of «Gersemia,» which he conceives to be identical with Rathke's Gorgonia florida and Ehrenberg's Nephthya Rathkiana, that 

 are recorded in the Synonymy. Marenzeller, however, having known the animal in question exclusively from VahFs drawing 

 and Rathke's incomplete description in «Zoologia danica,» and hence been without opportunity of observing it either dead or 

 alive, has very excusably confounded together two widely different Alcyonarians. Apart from the two above-mentioned speci- 

 mens of Rathke's typical species, we have likewise had before us several examples of Gersemia florida, collected on the Nor- 

 wegian North-Atlantic Expedition ; and hence we can show with absolute certainty that Rathke's species is wholly different from 

 Marenzeller's, and cannot be referred to the genus Gersemia. The said genus is thus characterized by Marenzeller: — «The 

 zoanthodeme erect, branched or tuberous, without subsidiary ramifications. The body of the polyp cylindrical, well developed; 

 the posterior part of the body of considerable length, either not at all or but very slightly retractile. The sarcosoma compara- 

 tively slender. No spicules in the septa. The wall of the body in the polyp, the tentacles and their pinnules abundantly 

 furnished with spicules. « 



From the description given below, it will appear how widely different is Rathke's species to Marenzeller's Gersemia 

 florida, and to that genus it cannot therefore possibly be referred. 



The basal part of the zoanthodeme is much dilated and attached, as a thick, flrm membrane, either to a stone or 

 to some other solid object. From the basal part, rises a very thick, fleshy, almost round trunk, grooved lengthwise by the large 

 and distinctly prominent longitudinal canals. Both the basal part and the trunk are, on their outer surface, to a greater or 

 less extent, incrusted, partly with sand and partly with the shells of Foraminifera (Biloculinæ). From the trunk proceed 

 numerous round, shallow-grooved branches, dividing into a multitude of branchlets, that again divide into still smaller rami- 

 fications, bearing each, as a rule, from 6 to 9 polyps, united at the basal part. 



The polyps are non-retractile, urceolate, with the posterior part of the body rather short, and rapidly tapering 

 towards the branchlets (the smallest ramifications), where it originates, thus giving to the polyps a pedicellate appearance. 

 The outer surface of the body is provided with 8 strong longitudinal ribs, consisting of several series of long, thorny spicules 

 placed one upon the other, extending across to the aboral surface of the tentacles. Between the aforesaid ribs are also 

 seen spicules ; and hence, on the polyps being some whatcontracted, — which is the case, for example, in spirit specimens, — the 

 body appears to be wholly surrounded by a calcareous armature. The tentacles are short, pyramidally pointed, with thick 

 pinnules, the latter having no calcareous deposit. 



