PORIFERA. III. 



95 



40. H. consanguinea n. sp. 



PL IX, Fig. 8. 



Incrusting; surface finely hispid. Spicula: megasclera; the skeletal spicules acanthostyli with a 



small or no head-swelling, they are divided into two groups, large, zuith a smooth apical part, 0-21 — 



0-29™'", small, entirely spined, cno — o-ij"""; the dermal spicules tornota, 0-15—0-10""" ; microsclera two 



forms, chelcr arcuata: 0-028 — 0-057""", contorted sigmata 0-014 — o-oij""". 



This species grows as thiu incrustations on living Brachiopods and one on a Retepora: the 

 sponge covers generally the whole shell and may thus reach a greatest extent of 16 mm ; it is exceed- 

 ingly thin, not reaching 0-5 n,m in thickness. The colour (in spirit) is whitish. The surface is short 

 and finely hispid. The dermal membrane is very thin and hardly observable. 



The skeleton. The dermal skeleton is not much developed and somewhat diffuse; it consists 

 of small bundles formed by a few spicules; the bundles stretch from the skeleton below up to the 

 dermal membrane. The main skeleton is constructed in the ordinary way and consists of acanthostyli 

 with the heads based on the substratum; the styli are not densely placed. The longer styli stretch 

 beyond the dermal membrane, thus giving rise to the hispidity of the surface. So far as I could 

 observe there is a very small amount of spongin at the base of the skeleton. 



Spicula: a. Megasclera. 1. The skeletal spicules are acanthostyli which are divided into 

 two well separated groups, large and small. The large styli are straight or generally slightly curved 

 near the base; they are thickest at the base but have no or only a small head-swelling; they taper 

 evenly from the base, but the apex itself is not long-pointed ; the styli are somewhat densely spined 

 in almost the lower two thirds, the spines being less dense outwards; at the base the spines are 

 somewhat large and blunt, for the rest they are small. The small styli have a similar shape as the 

 large, but they are spined in the whole length. The large styli have a length of o - 2i — 0-29 mm and a 

 diameter at the base of croi8— 0-025 """• The small styli are o - io — o-i3 mm long with a diameter at the 

 base of about 0-014""". 2. The dermal spicules are tornota which are somewhat thin, straight and 

 cylindrical; the ends have short points; they are not of a simple tornote shape in so far as one end 

 has a generally slight swelling; sometimes also the other end may show an indication of a swelling. 

 The length of the tornota is 0-15 — 0-19 mm and the diameter about 0-0025""". b. Microsclera are of two 

 forms, chela; arcuatae and sigmata. 1. The chelse have a slightly curved shaft and relatively small 

 end-parts, the alae are lobe-shaped and the tooth elliptical. The length of the chela is 0-028— 0-057 mm 

 and the diameter of the shaft 0-003— o-oo6 mm . 2 - The sigmata are thin and contorted, generally a 

 quarter of a turn; their length is 0-014 — 0-017 and the thickness o-ooo8 mm . The microscleres are seen 

 through the whole tissue of the sponge. 



This species shows some resemblance to H. (Hymeraphia) ?nucronata Tops, with regard to the 

 different categories of spicides, but the size of these is different for all forms and especially for the 

 tornota, and there is only one form of chelse in the present species. The species is easily distinguished 

 from the preceding by the sigmata and the tornote dermal spicules. 



Locality: Station 25, 63° 30' Lat. N., 54 25' Long. W., depth 582 fathoms, and at 70 32' Lat N., 

 8° 10' Long. W., depth 470 fathoms (The Ryder Expedition 1891 — 92). In all five specimens. The 

 localities lie in the Davis Strait and the Denmark Strait. 



