148 



PORIFERA. II. 



the tornotes seem to be quite horizontal and often scattered in the membrane. The main skeleton of 

 this species, as far as I have been able to decide from the slight material, is only little differentiated. 

 It consists of a rather dense, but diffuse framework of spicula-bundles and spicules, and no real network, 

 or, at all events, only a quite irregular one is formed. In the skeleton rather long and thick, but loose 

 fibres occur, but they have also a quite irregular course; these fibres, in which many spicules are 

 found alongside, reach a thickness of up to o-i2 mm . Spongin, no doubt, is present, but only to a very 

 slight degree. 



Spicula: a. Mega sclera, i. The skeletal spicules are straight or slightly curved acantho- 

 styli with an even and rather long point; the spiuulation is powerful, the length of the spines being 

 generally more than half the diameter of the needle. Generally they are gathered closely at the head- 

 end and continue over the tapering almost to the very point. Their length varies from 0-14 — o-2o8 mm , 

 and the thickness from 0-004— o-oo7 mm . Quite few fine developmental forms were seen. 2. The dermal 

 spicules are tornota; they are straight or a little irregularly curved; they are otherwise of a similar 

 form as in incrustans, but the ends are sharper and more lauceolately pointed; a slight narrowing is 

 almost always found below the end. The points are exceedingly slightly and finely spined, sometimes 

 smooth. In the fully developed tornotes the ends are equal or about equal. Their length is 0-13 — 

 _ . I jgmm ) anc j t ] ie thickness varies from ca. 0-0035— o-oo5 mm . b. Microsclera ; these are of two forms, 

 three-toothed isaucorse spatuliferae and sigmata. 1. The an corse are of the same type and of a 

 similar form as the small ancorae of the preceding species; they have an evenly curved shaft, and 

 three leaf-shaped teeth and a narrow ala at either end. Their length varies from 0-018 — o-030 mm , and 

 the thickness of the shaft is 0-0014 — o-oo2 mm . 2. Sigmata are small, of the common form, and more 

 or less contort; they are characteristic by their highly recurved ends. Their length is 0-018 — o-024 mm , 

 and the thickness is 0-0007— o-ooi4 mm . The ancorae are especially found in the dermal membrane, but 

 they are otherwise only present in small numbers, sigmata occur far more frequently. 



Locality: Faskrudsfjord in Iceland, depth between 20 and 50 fathoms (Horring), one specimen; 

 Jan Mayen, depth 50 — 60 fathoms (The Amdrup-Expedition), one specimen. 



6. M. pedunculata n. sp. 

 PL V, Fig. 2. PI. XV, Fig. 1 a— d. 



Club-shaped , stalked. The surface slightly shaggy. The dermal membrane thin . supported by 

 bundles op dermal spicules, and in places with horizontal spicules. The skeleton consists of polyspicular 

 primary longitudinal fibres connected by irregular transverse spicula-bundles and spicules. Spicula: 

 Megasclcra: the skeletal spicules smooth styli 0-36— o- 50""". the dermal spicules tornota 0-238 — 0-34""": 

 microsclera 0/ one form, aucorcr spatuli/enr 0-054 — o m o66""". 



This species is of a somewhat club-shaped form; below it has a rather short stalk attached by 

 a small basal expansion ; above it passes into a thicker part which in the best preserved specimen is 

 somewhat triangular and slightly compressed. This specimen has a height of 22 mm , and a thickness 

 above of io mm , the stalk is about 5 mm long and i mm thick. The smallest specimen is about io mm high; 

 it is more evenly club-shaped without any marked stalk. Of the specimens one is attached to a stone, 



