PORIFERA. II 137 



vary somewhat more. All forms of microsclera occur throughout the sponge; the}' are also found in 

 the skin, and especially in large numbers in the membranes of the canals. 



Embryos. In most individuals embryos were found; they were present in large numbers and 

 were lying rather close in the tissue. The embryos are globular, and their average size is 03 — o'5 mm 

 Of spicules only megasclera were found in almost all the examined specimens. These megasclera are 

 finely knotty, straight tylostyli; in the fine ones the head is most frequently found a little below the 

 end, while in the thicker ones the end itself is swollen. Their length was measured from 0-045 U P to 

 o-i3 mm by a thickness of o - ooi— o - 0O5 n "". Thus these needles are skeletal spicules, which accordingly 

 are the earliest occurring ones, whereas no dermal spicules were found. In a few embryos, in which the 

 stvli were of the largest sizes, also microscleres were found, that is to say developmental forms of the 

 aucorse; these forms were measured to a greatest length of o-oaS'"" 1 , but their form indicated that 

 the) belonged to the large form. Spicules were already present in all the examined embryos. 



Locality: We have a rather copious material of the species. Station 31, 66° 35' Lat N., 55 54' 

 Long. W., depth 88 fathoms; station 34, 65 c 17' Lat. N., 54 17' Long. W., depth 55 fathoms; station 127, 

 66° 33' Lat. N., 20 05' Long. W., depth 44 fathoms; Holstensborg (Bergendal); Egedesminde (Traustedt); 

 Jakobshavn (assistant Olsen); Jan Mayen, depth 55 fathoms (the Amdrup Expedition 1900); the Bay 

 of Skagestrand, depth 33 fathoms (Ditlevseu); east of Nolso, depth ca. 30 fathoms, at the northern end 

 of Nolso, depth ca. 100 fathoms (Th. Mortensen). The localities are situated off West-Greenland, north 

 of Iceland, off Jan Mayen, and off the Faroe Islands. 



Geogr. distr. The species is hitherto known from the coast of Jan Mayen (Marenzeller); from 

 the Orkneys, the Shetland Islands, the Hebrides, and the coasts of Great Britain and Ireland (Bower- 

 bank); the Sound (Levinsen); the coasts of France, at the Channel and at the Atlantic, for instance 

 the Bay of Biscay, at depths of ca. 96, 133, and 206 fathoms (the «Caudan , Topsent), and finally from 

 the Gulf of St. Lawrence (Lambe). In the seas in question it is thus distributed from 71 to 45 Lat. N. 

 It is chiefly a shallow water- and shore-species, and the greatest depth, from which it is known, I suppose 

 to be stations 19 and 32 of the < Caudan in the Bay of Biscay with a depth of ca. 206 fathoms (400 metres). 



Remarks: I have been able to determine this species with certainty, as I have examined a 

 specimen sent by the Rev. Mr. Norman; this specimen showed distinctly the spined ends of the tornota. 

 As will have been seen from the description, the species may be somewhat varying, especially with 

 regard to the size of the spicules, and it seems even to be able to vary still more than shown by my 

 material; thus Lambe I.e. gives the lower limit of the styli to o-i2 mm and of the tornota to o-i4 mm , 

 but here, perhaps, developmental forms are included. The species has surely often been described 

 under different names. As mentioned by Levinsen 1. c, it is thus this species O. Schmidt has 

 determined as fimbriata Bow., and, in Spong. des atlant Gebiet. 1. c, quoted from Denmark and Greenland, 

 which fact is shown by the specimens in the museum at Copenhagen. I suppose that it may also be 

 regarded as a certain fact that M. barentsi Vosm. 1. c. is identical with the present species, and this 

 seems also to hold good with regard to the M. barentsi mentioned by Lambe (Trans, of the Roy. 

 Soc. of Canada, 1894, XII, Sect. IV, 121, PI. II, figs. 9, 9 a— c). I also think that Hastatus Robertson/' Frstdt., 

 1. c, is the same species. With regard to both species the descriptions agree exactly with incrnstans. Of 

 the two varieties of incrnstans, typica and viscosa, mentioned by Topsent (Arch, de zool. exp. et gen. 



The Ingolf-Expedition VI. 2. l8 



