PORIFERA. III. 33 



b. Microsclera; these are of one form, eh else arcuatae, they have a curved shaft, the free middle 

 part of which is more than one third of the length of the chela, the tooth is elliptical, of the same 

 length as the pointed lobe-shaped ala;. The length is 0-021— 0-0257 mn ', inc diameter of the shaft is 

 0-0028 mm . The cheke occur richly especially in the pore-areas and the oscular wall, but they are also 

 otherwise found round about in the tissue. 



Embryos: In several specimens embryos were found round about in the tissue, and they are thus 

 not only found innermost, close to the axis, as declared by Carter 1. c. They are globular or oval, 

 of an average diameter of about 0-29 mm . Most of the examined specimens contained no spicules, but 

 some single were developed so far, that they contained spicules; these were dermal spicules, and they 

 quite resembled the developmental stages of the dermal spicules in the grown sponge. It is worthy of 

 notice, that the first occurring spicules here are the spiued dermal spicules, while elsewhere in the 

 Myxilleae it is the skeletal spicules which occur first. 



Remarks: As I have examined preparations of Carter's type-specimen, the identification is 

 certain. For the rest the description given by Carter is by far the best of all the descriptions published, 

 as he describes the skeleton and the inner cavities in somewhat detail. The species is also rather well 

 recognizable after his description, when the curious, diagrammatic way in which Carter made figures 

 of the exterior, is borne in mind. The points on the surface which Carter mentions and figures, are, 

 of course, the closed pore-areas; he mentions that they form low conical projections, which are formed 

 of acanthostyles "arranged in a whorl-like manner" and he figures this structure. Anything similar 

 I have not found in my specimens, but I think, that by a certain degree of contraction the spicules 

 around the pore-areas may very well present themselves in a way answering to Carter's expression. — 

 Armauer Hansen's type-specimens of Sclrrilla arctica and dura I have also examined, and they 

 proved to be the present species; his figure of the acanthostyles as oxea is erroneous. Armauer 

 Hansen concludes with a remark which shows, that he has well seen the conformity of his two 

 species, and the remark at the same time is very curious as he says: "Probably it would be more 

 correct to assign them to one species". I have also examined the type-specimen of Aruesen's Yvesia 

 lobata. — I also refer Topsent's Y. pedunculata and the same authors )'. pertusa from 1904 (but 

 not Y. pertusa 1892) to the present species; the first named species has relatively small aud somewhat 

 diffusely spiued acanthostyles, but this is a character, which according to my observations may be found 

 in G. pyrula, and otherwise the two species exactly conform. )'. pertusa Tops. 1904 seems to me to 

 be quite the same as the present species, and I really do not understand, why Topsent refers it to 

 his Y. pertusa established in 1892, which latter has typical acanthoxea as dermal spicules. 



Locality: Station 4, 64° 07' Lat. X., n 12' Long. YV., depth 237 fathoms; station 8, 63 56' Lat. X., 

 24 c 40' Long. W., depth 136 fathoms; station 27, 64 54' Lat. N., 55 10' Long. YV., depth 393 fathoms; 

 station 57, 63° 37' Lat. X., 13° 02' Long. YV, depth 350 fathoms; station 85, 63 21' Lat. X., 25° 21' Long. YV., 

 depth 170 fathoms; station 94, 64 56' Lat. X., 36 19' Long. W., depth 204 fathoms; station 95, 65 14' 

 Lat. X., 30° 39' Long. W., depth 752 fathoms; further it has been taken on 63 15' Lat. X., 9° 35' Long. YV., 

 depth 270 fathoms and 6i° 23' Lat. X., 5° 04' Long. YV., depth 255 fathoms (Wandel), and East of the 

 Faroe Islands, depth about 150 fathoms (Th. Mortensen). In all twelve specimens. The localities are 

 situated in the Denmark Strait, between Iceland and the Faroe Islands and South of the Faroe Islands. 



The Ingolf-Expedition. VI. 3. 5 



