PORIFERA. I. 



107 



ably, from O'Zj — 0'68'"", the thickness is in proportion 0'005 — o-oiyS""; a few, qnite fine needles, deve- 

 lopmental forms, are seen; but besides these, part of the needles l>'ing- between the said limits, especially 

 the comparatively long and fine ones, are presumably also developmental forms; it is, however, difficult 

 in all instances to decide with certainty which needles are developmental forms, as the fully developed 

 needles surely vary much in size; thus needles are found of a length of o'agS""" and a thickness of 

 0'0ii""°; on account of the proportion between length and thickness these needles convey the impression 

 of being fully developed, and when the question is of spicules of this length presumably only the 

 finer ones are developmental forms, b. Alicrosclera: i. Diancistra; in the present siDecies diancistra are 

 only found of one kind; they are chiefly of the same structure as the large diancistron of the prece- 

 ding species, but are distinguished from it by being longer and more slender, and generally the shaft 

 is a little bent; the recurved ends generally form a smaller angle with the shaft than in Bowerbanki; 

 the edge issuing from the shaft, decreases evenly towards the middle, so that the notch between the 

 two edges is longer and not so highly conspicuous as in the preceding species. Further these diancistra 

 are far less contort, not rarely quite plane. The length is between 0-19 and o-22"™, most frequently 

 it is o-aoS™". The thickness in the middle is o-oo8 — o-oio™". The development of the diancistra takes 

 place in the same way as in the preceding species, as shown on PI. XIX, fig. i c — d. The diancistra 

 are found in rosettes on the fibres, but this feature is not so distinctly marked as in the preceding 

 species; further they are, as already mentioned, found in rosettes on the membranes separating the 

 cavities, and they are also seen in the innermost layer of the dermal layer, which is presumably lined 

 bv the same membrane, and also here in beautiful rosettes; finally the diancistra are also found abun- 

 danth- in rosettes in the lower part of the sponge among the extraneous bodies. 2. Rhaphides; these 

 are especial!)- fine, the thickness is about o-ooo/™", and they have an average length of o-ii"""; they 

 occur in bundles, trichodragmata, containing a large number of rhaphides; they are found throughout 

 the sponge, but especially on the membranes and in the innermost part of the dermal layer. 



Rn/iarks: In this species <cellules spheruleuses» were found in large numbers in the dermal 

 layer and the membranes; they are quite globular or fusiform, densely filled with somewhat refringent 

 granules, and are in spirit of a light }-ellow colour; the size of the round ones is ca. 0-005— O'OoS™'", 

 the fusiform ones are somewhat longer. 



As has been mentioned under the preceding species I think that Topsent 1. c. under his 

 H. Joluisoiii has comprised more than one .species; the specimen of var. coiuplanata with rhaphides, 

 mentioned at p. 87, seems undoubtedly to belong to the present species. The H. papillata established 

 by Vosmaer 1. c, seems bv the occurrence of papillae and upon the whole by its outer characters to 

 agree with the present species, but the exceedingly incomplete and short description (2' , Hues) gives 

 no sufficient hold for a determination, and as the mentioned and figured spicules do not agree with 

 the present species, and rhaphides are not mentioned, the referring is doubtful. 



Locality: The present species has xipon the whole been taken on the same stations as the 

 preceding one, but in smaller numbers. Station 9, 64' 18' Lat. N., 27" 00' Long. W., depth 295 fathoms; 

 station 10, 64° 24' Lat. N., 28° 50' Long. W., depth 788 fathoms; station 27, 64" 54' Lat. N., 55" 10' Long. W., 

 depth 393 fathoms; station 35, 65° 16' Lat. N., 55^ 05' Long. W., depth 362 fathoms; station Si, 61=44' 



14* 



