Species of Echinonematous Sponge. 45 



face, areolate on the upper, growing proliferously upwards 

 into simple stem-like processes (s) and a thin wide flabellate 

 expansion (f). The latter, which is seated on a short stout 

 stalk, is formed apparently by the union of a number of simple 

 stems, which, fusing together basally, give rise to the stalk, 

 and then, diverging and branching radiately upwards and out- 

 wards, produce the fan-like plate, on which their course is 

 marked by radiating ridges costating both surfaces of the plate, 

 while the lines along which they unite are indicated by radia- 

 ting furrows left between the ridges. These furrows are fre- 

 quently bridged over by irregular transverse connexions, and 

 thus becomeconverted into series of deeper or shallower irregular 

 pits. Two open window-like spaces (f) perforating the midst of 

 the plate are due to the failure of the component ribs in these 

 places to unite. The lower half of the incrusting base and the 

 central two thirds of the stems and ribs grey in colour and dense 

 and compact in texture ; succeeded by an irregularly cavernous, 

 sulphur-yellow, intermediate layer, which supports a thin 

 drab dermal membrane, through which, in places, a number 

 of large pointed spicules project, rendering the surface hirsute 

 (PL VI. fig. 2). 



Skeleton. The hard parts are those of the axis or base, of 

 the intermediate and dermal layers, and of the sarcode. 



Axial spicules with a smooth cylindrical shaft, termi- 

 nated at each end by a spherical microspined inflation, 

 0-0075 inch long, 0*0005 inch diameter (PI. VI. fig. 4) ; 

 confusedly entangled together in a felt-like manner (PI. VI. 



Intermediate spicules of two kinds : — (i.) a long, robust, 

 curved, conical acuate, sharply pointed at one end and gene- 

 rally spherically inflated at the other, inflation usually smooth 

 (PL VI. fig. 3), sometimes minutely spined (PL VII. fig. 

 8) ; length - 041 inch, diameter of shaft 0*0018 inch, of head 

 0*002 inch ; collected in short columns, projecting at right 

 angles from the axial core, in the external layer of which 

 the inflated ends of some of the spicules are imbedded (PL VI. 

 fig. 2) ; (ii.) a smaller curved, spined acuate, 0*01 inch 

 long, 0'001 inch broad, pointed at one end, inflated spheri- 

 cally at the other, spines on inflation blunt (PL VII. fig. 16), 

 or pointed, with the points directed from the head to the 

 other extremity of the spicule (PL VII. fig. 17) ; spines of 

 the shaft commencing about the middle of its length, and 

 extending within a short distance of its point, conical, re- 

 curved, numerous ; inflated heads of the spicules imbedded 

 in the axial cord or in the penicillate columns of larger 

 acuates, pointed ends projecting echinately (PL VI. fig. 2). 



Dermal simple, straight, conical acuates, rounded obtusely 



