REPOKT ON THE HEXACTINELLIDA, 247 



tliorougliness by Thomas Higgin, and the result is to show that it must shiiply 

 be included in the genus Pheronema. Since I have not myself been able to examine 

 Pheroncma hem{s2')hiericiim, I will here content myself with citing the last and most 

 thorough description, that of Higgin/ and with shortly summarising the most essential 

 characteristics. 



According to Higgin, the sponge is in form " like a small bird's nest, the bottom of 

 which is flat, mth a well-defined edge : the sides are rounded ; and the sponge attains its 

 greatest diameter about one-third of the way down from the edge of the hollow of the 

 nest, towards the base." According to his figure on PL XXH. fig. 3 the shape is like 

 that of a prehistoric Greek clay urn, and exhibits a convex surface above and below the 

 annular pad which occupies about the median third of the lateral wall. The maximum 

 transverse diameter measures about 10 to 12 cm., and the height about 9. The upper 

 flatly spherical cavity is at the margin 8 to 9 cm. in width, and is 4 cm. deep. The 

 length of the anchor needles in the basal tuft is 8 to 9 cm. On the superior, sharply 

 defined margin there is a wreath of varying length and 1 to 3 cm. in breadth, composed 

 of long straight pointed spicules, which project at right angles. The lateral usually pro- 

 jecting annular zone is covered with " whisker-like bundles of long spicules which issue from 

 circular holes the edges of which are slightly raised, each bundle consisting of a dozen or 

 more spicules. Around the circumference of the base are arranged loose fascicles of 

 anchoring spicules, from 7 "5 to 8 cm. in length, and having a diameter of about 12 mm. 

 measuring along the edge of the base, by 6 mm. to 10 mm. A few scattered short 

 spicules project here and there from the base generally, but there are no bundles other than 

 those around the edge. The anchoring spicules are of one kind only, viz., smooth, fusiform, 

 terminating at the free end in two opposite hooks; there are no spined forms. The spicules 

 of the whisker-like tufts are plain, fusiform ; the spicules of the erect fringe round the labrum 

 are also fusiform and smooth throughout, but there is an appearance of spines on some 

 towards the free end." In the surface reticulation T. Higgin found four kinds of spicules — 

 " (l) pentacts, whose four tangential arms are equally smooth and opposite or at right 

 angles to each other, inclined slightly downwards or inwards ; the shafts of the larger 

 spicules are 12 mm. long; (2) long, slender, acerate spicules, thickly covered with short 

 sharp spines, all jjointing towards one and the same end of the shaft ; (3) smooth acerates 

 with the cross on the central canal ; (4) plumose spicules, of shapes intermediate between 

 one with a very thick shaft, short and bushy looking, with long, strong, bluntly ended 

 arms, and another -with small, short, fine arms and a long feather-like shaft ; the crucial 

 arms of which, thickly studded with short obtusely pointed spines, are bent downwards, 

 as if to embrace or fit to the arms of the large spicules on which they rest. The strongly 

 woven together basket work of the interior, as seen through the investing network, 

 is composed of: — (1) smooth spicules of the sexradiate type (that is, acerate with simply 



1 Ann. and Mag. Nat. Hist., rer. 4, vol. xv. p. .377 



