J 2 PORIFERA. I. 



under the skin is seen as a unispicular, irregular net work, from the nodes of which the ends of the 

 primary fibres rise. 



The skeleton is chiefly constructed according to tlie principle common in the Chalinines. It 

 consists for the greater part of a rather regular network of more or less quadratic meshes. In the 

 middle of the stalk and the leaf a more open and irregular network is foiind in which primary and 

 secondary fibres are not to be distinguished; from here fibres issue towards the surface; these primary- 

 fibres are directed a little upward on their way to the surface, but they bend a little, so that tliev meet 

 it at a right angle; especially in the lower part of the sponge the bending upward is quite slight, 

 and the fibres go almost quite horizontally to the surface; in the upper part of the leaf the bending 

 upward is more conspicuous. The secondary fibres consist only of single spicules comiecting the 

 primary fibres, and forming together with those the reticular work, but they do not form, or form 

 only to a small degree, coherent fibres. The primar)- fibres are mostly unispicular; they may, however, 

 especially in the lower part of the sponge, be polyspicular, but only with a few spicules alongside. 

 The distance between the primary fibres is about the length of a spicule, or ca. 0-15 — o-iS'""'. The 

 spongin is only present to a small degree, it is distinctly seen in all the nodes, and under sufficiently 

 magnifying powers it may in most places be seen as an exceedingly thin layer covering the fibres; 

 the elastic consistency of the sponge implies also that the fibres must be richer in spongin than is 

 the case in the J^em'era-species. In the stalk the spongin is more richly developed than higher up 

 in the sponge. Besides the regular skeleton described above, some more fibres are found, viz. some 

 rather powerful ones, beginning in the stalk and running as longitudinal fibres up through the sponge 

 branching off and anastomosing. Down in the stalk the}' are polyspicular and surroimded hv a strong 

 spongin-sheath, here tliey may reach a thickness of o'i2"""; in branching off upwards thev become 

 thinner, and the number of spicules smaller down to only a couple of spicules, or they become quite 

 unispicular; the spongin also decreases, but ma\', however, still be seen as a thin, but distinct sheath. 

 Outside the skeletal net some spicules are found dispersed; they are generally shorter and finer than 

 the spicules of the skeleton. 



Spicula are slightly curved, sometimes straight or almost straight oxea, evenly and rather 

 gradually tapering; the curve sometimes is quite even, but sometimes it may also be confined more 

 or less distinctly to the middle part. The length is between 0-19 — 0'22""", most frequently it is about 

 caoS""", the thickness is o-oio — ooia™'". As before mentioned some spicules are found spread in the 

 sponge; they are found in no small numbers, and are shorter and finer, up to quite fine ones; by all 

 transitions in size they are connected with the spicules of the skeleton. 



With regard to the outer features this species recalls the description by Fristedt of the Cha- 

 lina groenlandica from the eastern coast of Greenland, mentioned below, but the spicules of this latter 

 species are abruptly pointed and more curved. 



Locality. Only one specimen of this beautiful species has been taken. Station 34, the Davis 

 Strait, 65° 17' Lat. N., 54" 17' Long. W., depth 55 fathoms; the specimen is attached to a stalk of a hy- 

 droid together with two species of calcareous .sponges, an ascidian, a couple of hydroids, a bryozoa, 

 and two octactinite of the genera Voeyingia and Paranephtkya. 



