Marine Sponges from Japan. 395 



similar defined circular apertures about l-12th in. in diameter 

 existing on the surface of the stem, close to the commence- 

 ment of the structure below, where, by thickening of the 

 tissue, all but the extreme ends of the branches have become 

 imbedded, which thus look like vents ; excavation deep, 

 narrow, and conical towards the bottom, where it occupies 

 the centre of the stem, fenestrated on its surface, as above 

 described. The upper part of the specimen having been much 

 worn away (for it had been dragged out of greenish sandy 

 mud for preservation, where, being dead, it must have been 

 buried for some time previously), I am unable to state how the 

 excavation and its surrounding tubo-branched structure termi- 

 nated above , but probably in the same characteristic form and 

 with open mouths as in the smaller structure below. Con- 

 sistence firm and elastic. Colour, pore-structure, and small 

 excretory canal-system, that is of the fleshy part, when the 

 specimen was fresh, probably the same as in the Euritidje, 

 together with the large excretory system, which consists of 

 the tubo-branched canals terminating cloacally in open 

 mouths on the outside of the excavation or surface of the 

 specimen. Main fibre of the tubulated lamina reticular, con- 

 sisting of a more or less quadrangular oblong network, in 

 which the longest diameter of the interstices is in the direction 

 of the tube, strengthened or thickened on each side by a less 

 regularly reticulated growth, of which the smaller tubulated 

 structure is almost entirely constructed, the more regular net- 

 work being confined to the larger tubulation in the upper part 

 of the head. Skeletal fibre reticulated sexradiately, not in- 

 flated at the joints, microspined throughout, formed upon 

 small regular sexradiates, which may be seen in its inter- 

 stices preparatory to becoming incorporated. Sexradiate spi- 

 cule consisting of six fully-developed arms, straight, inflated, 

 and abruptly pointed at the end, microspined throughout, 

 especially over the end, averaging 34-6000ths in. in diameter, 

 but very variable in size, owing to the thickening preparatory 

 to incorporation. Three other forms of loose spicules, viz. : 

 1, the barbula, as already described and illustrated under 

 Farrea occa] 2, scopuline spicule or " Besengabel," of which 

 I have only met with one instance, and that only of the four 

 capitate branches or rays of the head, the rest being incorpo- 

 rated with the skeletal fibre, whereby it had been thus 

 retained, since, as usual in such buried specimens, all the 

 loose spicules have disappeared ; 3, the rosette (that only 

 exists in one part of the foot which presents the freshness of 

 life), sexradiate, without central inflation, arms straight, 

 smooth, each supporting five rays, more or less, of which four 



