PORIFERA. III. 



3. G. carnosa Tops. 



PI. Ill, Figs. 2021, PI. V, Fig. 4. 



1904. Yvesia carnosa Topsent, Resultats des camp, scient. du Prince de Monaco, Fasc. XXV, 198, PI. XV, fig. 19. 



Plate-shaped and incrusting, or higher and more massive. Surface rugose and wrinkled, without 

 projecting spicules. Oscula spout-shaped. The dermal membrane a thin film. The dermal skeleton 

 formed of acanthoxca which are very scattered and often only found in the dermis in -very small 

 number. The main skeleton consisting of fibres which from the base or the middle radiate towards the 

 surface; there are no transverse fibres, but the acanthoxea are scattered between the fibres. Spicula: 

 megasclera; the skeletal spicules are polytylote tornota, o-j? o-tf""", the dermal spicules acanthoxca 

 0-178""* ; microsclera not present. 



The Ingolf-Expedition has taken three specimens of this species; one grows as a plate on a 

 specimen of Biemma rosea and has a greatest extent of about 25 mm , and a greatest thickness of 3""", 

 the second specimen grows on a shell of Pecten aratus as an incrustation with a greatest extent of 15"""; 

 these specimens have thus in outer shape a resemblance with the specimens described by Topsent, 

 which latter, however, reached to a greatest extent of 55""". The third specimen is a small, oval 

 body, of a length of 7"""; it has two oscular cones in one end, the other end shows a somewhat broken 

 surface and besides some adhering bottom material; the specimen has thus probably been attached 

 with this end and has thus been erect The colour (in spirit) is lighter or darker brown, in one 

 specimen quite white; Topsent's specimens were blackish, one or the other of the colours is certainly 

 due to the action of alcohol. The consistency is somewhat firm and elastic. The surface is somewhat 

 wrinkled and folded, but otherwise smooth. The dermal membrane is thin but somewhat solid, it is 

 not easily separable, and it is provided with spicules only to a very slight degree. Pores or pore- 

 areas I have not seen, probably they are closed and must have disappeared in the folded and wrinkled 

 dermal membrane. Of oscula as said two were found on one of the specimens, while the two others 

 showed none. 



The skeleton. The dermal skeleton is in this species almost not developed, as there are, at 

 all events in by far the most places, only rather few, scattered acanthoxea in the dermis. The 

 main skeleton has a somewhat similar structure as in the other species; it consists of fibres which 

 radiate towards the surface, are branched and support the dermis, but do not pierce it; the outermost 

 fibres are as a rule thin, but here and there also very thick fibres go to the surface; in the interior 

 the fibres are very thick and strong. The fibres go in the plate-shaped specimens not parallel from 

 the base to the surface, but they seem to have a more or less extended centre at the base, from 

 which they radiate to the surface; in the erect specimen there are thick spicular parts at the base 

 and in the middle, from which fibres radiate out. There are no transverse connecting fibres, but 

 acanthoxea are scattered between the fibres. The fibres consist of tornotes; the skeleton in the oscular 

 cones are formed of fibres of tornotes, but no acanthoxea were seen here. Spongin was not observed. 



Spicula: a. Megasclera; i. The skeletal spicules are tornota, they are straight, the ends are 

 somewhat long-pointed, but outermost often a little stubby; they are distinctly polytylote. The length 

 is 0-37 0-47 mm and the diameter is between 0-005 anc ^ 0-007 mni . The ends are generally not equal, but 



