242 THE VOYAGE OF H.JI.S. CHALLENGER. 



tlie Brazil coast, off Macio, to the east of the mouth of the San Francisco (Station 124, 

 lat. 10° 11' S., long. 35° 22' W.), from a depth of 1600 fathoms, and a red mud ground. 

 Several portions of the basal tuft, and of the lateral wall, with vestiges of the external 

 skin, are alone preserved. 



For my study of the tissue and the disposition of the various spicules, the specimens 

 collected by Mr. John Murray were especially satisfactory, owing to their excellent 

 preservation in absolute alcohol. These specimens exhibited an ellipsoidal form, and 

 the body measured, exclusive of the basal tuft, 5 cm. in length, and 4 to 5 cm. in 

 maximum breadth. The circular oscular opening at the superior pole is surrounded by 

 a wreath of vertically projecting, marginal spicules, lias a diameter of 12 mm., and 

 leads into a smooth- walled, cylindrical, inferiorly truncated gastral cavity, 25 mm. in 

 depth. From the whole external lateral surface, fine, pointed, radial spicules project in 

 loose bundles, 2 to 3 cm. in length. These are, however, irregularly disposed, with the 

 exception of certain closely set, somewhat longer spicules, which form an annular zone, a 

 few mm. in breadth, about 10 mm. below the marginal fringe. On the lower basal end 

 of the sponge, there is a large number of slender (1 to 2 mm. in breadth) tufts of long 

 flexible spicules, 30 to 40 cm. in length, which interlace abundantly in the thick felt-work 

 of the basal tuft. The indi\'idual slender bundles are however distinctly separate as 

 they issue from the sponge-body. The external surface of the sponge exhibits a delicate 

 dermal network, marked, especially in the dried specimens, by stellate knots at tolerably 

 uniform intervals (PI. XLIII. fig. 1). 



The ellipsoidal shape may be regarded as characteristic (jf the general form of the 

 body {cf. PI. XLIII. fig. 1, and W^-ville Thomson, loc. cit., pi. Ixvii., pi. Ixix. fig. 1), 

 although a comparative survey of all the forms before me reveals a slight difference 

 in this, that the larger, and therefore probably older specimens, are somewhat more drawn 

 out longitudinally, the smaller younger forms are approximately spherical, while the very 

 smallest, less than a pea in size, often exhibit, as Wyville Thomson has shown, the form 

 of a hen's egg with an inferior pointed pole (Wyville Thomson, loc. cit., pi. Ixxi.). 



As is noted in Wyville Thomson's careful investigation of the siliceous spicules of 

 Pheronema carpenteri, the parenchyma, which is on the whole only slightly massive 

 but is penetrated by countless lacunge and wide passages, contains among the larger 

 independent strictly parenchymal spicules, medium-sized, rarely large oxyhexacts, while 

 long, slender, flexible oxydiacts predominate. These are either smooth or thickl}^ beset 

 with appressed uniformly directed barbs, and are for the most part radially disj)osed 

 towards the external or'gastral surface, with the distal pointed end projecting for a variable 

 distance beyond the surface. Besides these, there are in the parenchyma a large number 

 of short, strongly developed uncinates, 0"2to 0"3 mm. in length, with but short spines or 

 barbs (PI. XLIII. fig. 5). Finally, there occur in the parenchyma small simple oxy- 

 hexacts, with smooth straight rays. That the strong and somewhat large smooth 



