REPORT ON THE HEXACTINELLIDA. 227 



lenctli of O'l mm., a long, narrow, axial rod with central teeth, and at each end, a narrow 

 bcll-shaj^ed umbel, occupying about a third of the total length, and provided with eight 

 rays, which have no great breadth, and which have terminally a rather straight course 

 (PL XXVIII. fig. 13). More rarely larger amphidiscs occur, of similar form, but with a 

 length of 0-2 mm., and a proportionate breadth (PL XXVIIL fig. 14). Besides these 

 numerous small amphidiscs occur from 0'03 to 0'02 mm. in length, exhibiting the same 

 form as the above, but lying tangentially in the dermal membrane (PL XXVIIL fig. 12). 



I was not able to examine the spicules of the marginal fringe. The pinuli of the 

 gastral surface and of the associated diverticula difi'er from those of the dermal region in 

 this, that the distal ray is slimmer, shorter, and not tufted, and that the four basal rays 

 are both relatively and absolutely longer than those of the dermal pinuli. In the basal 

 pad at the lower end of the sponge body, there are numerous strongly developed 

 spicules with a variable number of rays which exhibit toothed rounded ends (PL XXVIII. 

 figs. 10, 11.) 



Among the Challenger material there is a basal tuft of strong spicules much encrusted 

 with Palythoa, which bears a striking resemblance to the specimen figured by Bocage 

 {Joe. cit.), and very probably belongs to the species Hyalonema lusitanicum. I have 

 figured it in its natural size in PL XXXIX. fig. IG, and have investigated the few 

 persisting remnants of the sponge-body. The form was obtained at Station IV. to the 

 south of Cape St. Vincent, lat. 36° 25' N., long. 8° 12' W., from a depth of 600 fathoms 

 and a blue mud ground. From the upper end of the straight cylindrical form, which 

 measures 20 cm. in length by 10 mm. in breadth, some broken basal spicules project. From 

 the lower end shreds of a Palythoa encrustation hang down, but the bundle of spicules is 

 broken off. That the somewhat conical point turned upwards in the figure, is really 

 the superior pole, which supported the sponge-body, and had a few projecting spicules 

 inserted in it, is best demonstrated by the examination of the few small remnants of 

 the lost body, which persist loosely bound up with the Palythoa crust. The siliceous 

 elements recognisable in the traces of the basal pad are firm spicules with six to two 

 terminally rounded, cylindrical rays (PL XXXIX. fig. 17), which are beset with conical 

 elevations of variable size either throughout their whole extent or only at their ends. 

 On the larger conical elevations, small secondary teeth very frequently occur (PL XXXIX. 

 fig. 18). 



Unfortunately neither the results attained by Barboza du Bocage in his original 

 research on Hyalonema lusitanicum, nor those of my investigation of the above described 

 form, which is probably to be identified with Bocage's, are sufiicient to establish any 

 definite diagnosis of the form and structure of the species. Whether the much injured 

 specimen which I examined in the British JNIuseum is really the same as the root-tuft 

 described by Bocage in 1864 is likewise doubtful, although the label certainly referred 

 the specimen to the discoverer himself. 



