io . PORIFERA. III. 



the coasts of North Africa, in the Bay of Gabes and at la Calle (Topsent). The species is thus hitherto 

 known from 65 to 34 Lat. N., and between 6o° Long. W. and io° Long. E. As to the depth some of 

 the specimens of the Iugolf Expedition are taken in considerably greater depths than those from 

 which it was known hitherto; the greatest depth recorded was 95 fathoms, while it was taken by the 

 Ingolf Expedition in depths down to 582 fathoms. Its bathymetrical range as known now is in all 

 from the very coast even above low-water mark (Bowerbank) down to 582 fathoms. 



Remarks: If the rules of nomenclature were adhered to strictly, the present species should 

 have a new name, as it is not identical with the well known Halisarca Dujardinii Johnst. Bower- 

 bank thought, when he examined the present species, that Johnston had overlooked the spicules, 

 and he identified it therefore with Dujardinii. Already Schmidt has noted (Zweites Suppl. zu den 

 Spongien des adriat. Meer. 1866, 16) that this must be erroneous. Gray however in 1867 followed 

 (1. c.) Bowerbank. Topsent in 1888 (I.e.) placed the species in the genus Dcndoryx, and referred it 

 later correctly to his genus Leptosia, but he did not alter its name, which should properly have been 

 done, since Bowerbank's determination was erroneous. As the species is well known now under 

 the name Dujardinii I shall however make no change. 



46. H. primitiva n. sp. 

 PI. X, Fig. 6. 



Incrusting; surface smooth. Spicula: megasclera ; the skeletal spicules acanthostyli with a slight 

 head-swelling, entirely spined or the larger with a smooth apical part, 0-119 — o-jj'""', not divided into 

 two groups; the dermal spicules strongyla, slightly polytylote, 0-196 — 0-28""". No microsclera. 



This species grows incrusting on shells of Brachiopods, mussels and barnacles; it has a greatest 

 extent of about 20 mm , the thickness is about 0-5 mm . The colour (in spirit) varies between dark yellowish 

 and brown. The surface is smooth. The dermal membrane is a distinct but thin film; it was on my 

 specimens often destroyed to a high degree. Some canals are seen shining through the membrane, 

 and some oscula are present as circular openings not elevated over the level of the surface. 



The skeleton. The dermal skeleton consists of bundles or quite short fibres stretching from 

 the main skeleton, often almost from the base, to the dermal membrane; the spicules in the bundles 

 are penicillately spread towards the membrane and support it, but they do not pierce it. The mem- 

 brane itself is not provided with spicules or at all events only with some few, lying singly and 

 scattered; only around the oscula the structure is different; short fibres appear here in the membrane, 

 stellately arranged all round the opening, towards which they unite in such a way, that the opening 

 is surrounded by radiately arranged, but not dense-lying single spicules. The main skeleton is of the 

 ordinary arrangement, the vertical acanthostyli are somewhat densely placed; the longest of them 

 reach just to the dermal membrane. There is a considerable amount of spongin at the base, forming 

 a more or less continuous basal layer. 



Spicula: a. Megasclera. 1. The skeletal spicules are acanthostyli, which have only a slight 

 head-swelling; they are straight or, when longer, slightly curved near the base; they are somewhat 

 densely spined with spines of medium size; in the longer spicules the spines are small and scattered 



