PORIFERA. I. 97 



are found in almost every cutting of the sponge, the probabiUt>- is that they belong to it. This be- 

 lief is also favoured by the fact that the\- are mentioned b\- Fristedt as found in his specimen, 

 which is, in spite of the scarcely quite correct figure of the large sigma, surely identical with the 

 the species before me')- The small sigmata are much smaller than in the preceding species; they are 

 of the common form, and are plane; their length is between o'OoS — o'Oi'"", and the thickness may be 

 given as O'OOO/""" or still finer; these sigmata are exceedingl}- numerous, as well in the dermal mem- 

 brane as throughout the sponge. 2. Rhaphides of two sizes, both considerably larger than the corre- 

 sponding rhaphides in the two jareceding species. The long rhaphides have a length of 0-25 — 0-268'"", 

 and a thickness in the middle of ca. 0-002'""'. Their ends are produced into long tapering, fine points. 

 They are always straight, and if some are seen to be curved, when a piece of the sponge is examined 

 under the microscope, the cause of this fact cannot be that they have such a form, but it must be 

 due to a force acting on them. These rhaphides occur both scattered and in bundles containing a 

 rather large number of rhaphides. The short rhaphides are fusiform, their length varies from o-o8 

 — o-i""'", and the thickness is about 0-0028'"'°. These rhaphides are chiefly found in bundles that seem 

 most frequenth- to contain a rather large number of rhaphides. Both kinds of rhaphides are found 

 abundantly as well in the dermal membrane as through the whole sponge. 3. Commata; these are 

 only found in very small numbers, but like the large sigmata the>' are found in every cutting; they 

 are small, their length being ca. O'OoS""", and the thickness at the head end about o'ooi'"'". 



Gciiumila- / In this species Fristedt mentions the same bodies as have been mentioned in 

 the two preceding species, and which he takes to be gemmula;. He figures these bodies PI. 24, figs. 

 44 — 45. In the specimen before me I have only seen the small silicious globules that are found in 

 the wall of the mentioned bodies, singly or in small groups, while the piece of Fristedt's original 

 specimen I ha\e had for examination, short-s the gemmulse-like bodies abundantly; they are most fre- 

 quently quite globular, of a diameter of about 0-08"""; the>- are formed of silicious globules imbedded 

 in, or situated inside of, a membrane which is, perhaps, made of spongin; on the other hand I have 

 not been able to find the depression in the wall mentioned by Fristedt (a small depression like 

 that in the globular spicules of Geodia:), and I suppose that it is not really found, but is only due 

 to the refraction (PL XVII, fig. 2 f|. In the bodies that seem to be quite finished, the globules have a 

 diameter of ca. o'ooj""", while in others, mostly seen as loose groups of globules, it is considerably 

 smaller, down to 0-002'"'", or still smaller. The globules of the same group are always of about the 

 same size, so that all the globules belonging to one of the gemmula-like bodies, appear to be begun 

 and developed contemporaneously. 



The reason why these bodies ha\e here been termed gemmulse, is only that they recall to 

 ^ome degree the gemmulse of the spongillse, and presumably serve the propagation of the sponge; it 

 is only httle probable that their function should be the same as that of the gemmuls of the spongillse, 

 as the question is here of species from rather considerable depths (78—976 fathoms). 



Locality: The Denmark Strait 66= 20' Lat. N., 65- 12' Long. W., depth 96 fathoms (Wandel), one 

 specimen. 



I) Fristedt 1. c. does not mention that these sigmata are so small in number, and j-et they must surely have been 

 so also m his specimen, as I have not even been able to find any large sigma in the little piece of his specimen I have had 

 for examination, but then this piece also consisted almost only of naked fibres. 



The Ingoll-Expedition. VI. i. ^3 



