PORIFERA. II. 



131 



Of this species we have only a small, poor fragment, so that the description must chiefly be 

 restricted to the spicules. As to the form of the sponge nothing can be said; the fragment is longish 

 and has a greatest extent of i4 mm . The consistency is of a middle firmness. The colour (in spirit) is 

 yellowish. The dermal membrane is mostly destroyed; it seems to have been a thin film, supported 

 in the common way by dermal spicules. Pores and oscula were not seen. 



The skeleton. The dermal skeleton consists of dermal spicules, and, in spite of the destroyed 

 dermal membrane, it may be seen to have been arranged in the common way as more or less erect, 

 penicillate bundles. As to the main skeleton, on the other hand, I can say nothing definite, as the 

 fragment in hand may perhaps have been highly squeezed and pressed; in its present state the 

 skeleton appears partly as irregularly arranged spicules and partly as spicula-bundles. No spongin was 

 to be seen in the skeleton. 



Spie 11 la: a. Megasclera. 1. The skeletal spicules are oxea; they are slightly curved, evenly 

 tapering, and the point is rather long. Their length is 0-54— 075™™, the thickness is ca. cron — o-oi7 mn) . 

 2. The dermal spicules are also oxea, but by the form of their ends they approach somewhat to 

 tornota; thev are straight or quite slightly curved, and they taper a little towards the ends, the point 

 is even, but short. Their length is 032 — o - 44 mm , and the thickness in the middle is o-oo6— o-oio mm . 

 b. Microsclera; these are of two forms, chela; arcuatse and sigmata. 1. The chelae arcuatse are of 

 a rather broad and compact form, the shaft is rather highly curved, the tooth is elliptical, more or 

 less rounded, sometimes a little cut off at the end; there is a tuberculum, pointed downward; the alae 

 are of the same length as the tooth, and are more rounded. In contradistinction to the chela of the 

 preceding species the shaft is here highly flattened. Their length varies from 0-026 — o-0429 n>m and the 

 thickness of the shaft from 0-0025— O'0o85 mm , according as it is seen from the side or from the front. 

 Very few developmental forms were seen; they are already highly flattened at an early stage. 2. Sig- 

 mata; these are of the common form and more or less contort; their length may upon the whole 

 vary from 0-02 1— o-o64 mra , but it is rarely less than o-043 mm , so that the small forms are rarely seen. 

 The thickness is upon the whole 0-0014— o-oo28 mm . Both forms of microsclera occur in very large 

 numbers, and through the whole sponge; the chelse are seen in enormous numbers closely packed in 

 the dermal membrane. 



Locality: Station 78, 6o° 37' Lat. N., 2 f 52' Long. W., on the eastern slope of the Reykjanaes- 

 ridge, depth 799 fathoms. 



Myxilla O. Schmidt. 

 (Dendoryx Gray 1867). 



The form varying, from inc rusting to lumpily massive, cushion-shaped, or forming more or less 

 round masses, sometimes somewhat lobate; then more or less irregularly leaf-shaped, or finally club-shaped, 

 stalked. The skeleton a polyspicular reticulation, which may be more or less irregular, sometimes rather 

 diffuse. In the erect forms longer, primary fibres are found. It is no rare form that the reticulation consists 

 of triangular meshes, which may be more or less regular. The dermal skeleton consists chiefly of erect 

 bundles of dermal spicules, sometimes also horizontal spicules are found. Spongin is found, but almost always 



17* 



