460 ASTROSCLERA WILLEYANA, THE TYPE OF A yE\V FAMILY OF SPONGES. 



for it'. In November I received from Mr Kirkpatrick of the British Museum another 

 specimen of the same or a closelj" allied organism, which was collected in the boring 

 expedition to Funafuti, one of the Ellice Islands h'ing about a thousand miles to the 

 N.E. of Lifu. This was obtained at the depth of 100 fathoms on the outer slope of the 

 western side of the island. 



Before proceeding to details it may be stated that the hard parts consist of solid 

 polyhedral elements united to form a continuous skeleton. This is penetrated by canals 

 which branch and anastomose freely, and open to the exterior by apertures on the upper 

 surface. The canals are occupied by soft tissues which also cover the upper surface, 

 and are continued for some distance down the sides. 



External Characters. The Lifu specimens are cj-lindrical in shape, and measure 

 about 10 mm. in height and 5 mm. in breadth. The base is slightly spreading, the 

 sides smooth and imperforate, and faintly marked by annular constrictions, and the upper 

 surface gently convex. In three of the specimens the growth has occurred at right 

 angles to the surface of attachment (Fig. 1), but in the fourth (Fig. 2), whose attach- 

 ment appears to have been to a vertical surface, the axis is curved. The rounded upper 

 surface is closely pitted by the openings of the canal system, those at the periphery 

 being smaller than the others. 



In three of the specimens the openings are disposed indefinitely (Fig. 2 «), but in 

 the fourth (Fig. 1 «) there is a somewhat different arrangement. The upper surface 

 of this specimen is oval in outline, and about a point nearer one end of the long 

 axis than the other some seven grooves are disposed in a radiate manner. The 

 grooves show a tendency to branch at their outer ends, before they are lost in the 

 irregularities of the surface ; and one of them, which lies in the long axis, gives rise 

 to two subsidiary grooves which however are not disposed symmetrically about it. 

 The openings of the canal system are to be seen in the floors of the grooves as well 

 as on the parts of the upper surface lying between them. The soft tissues here 

 cover the surface, and it is not obvious that the pores in the grooves, or at the 

 centre from which they radiate, are larger than the others. A comparison of it with the 

 Funafuti specimen, however, renders the existence of larger pores in these situations 

 not improbable. The grooves are probably the initial stages of radially disposed canals. 



The specimen from Funafuti (Fig. A, 1 — .5) has grown attached by a short stalk 

 (A, 1, St.) about 6 mm. wide at the base, which expands into a broad, nearly circular 

 disc (d — d), convex above, and resembling the pileus of a mushroom in shape. The 

 diameter of the disc is about 20 mm., and the distance from the broken end of the 

 stalk to the centre of the upper surface of the disc is 1(J mm. 



A smooth, imperforated, cortical layer covers the outer surface of the stalk and 

 under surface of the disc, and presents concentric ridges and grooves, marking lines 

 of growth (A, 2). The upper surface of the disc is in part perforated by pores, whose 

 arrangement is described below. 



There appears to have been an interruption to the growth of the specimen after 

 the formation of the disc, and the later extension has taken place not uniformly, but 



' The definition of the species, i.e. of the family which it constitutes, is here given for the first time, p. 479. 



