Sponges from the Atlantic Ocean. 399 



flattened sides respectively, composed of radiating, columnar 

 structure internally, each pillar ending on the surface in a 

 little stelliform head, which, in juxtaposition, produces the 

 tessellated appearance mentioned ; the siliceous balls at matu- 

 rity form the crust, and are scattered throughout the sarcode 

 of the outer part of the body-substance and zone, as before 

 stated, in all stages of growth, where their gradationary deve- 

 lopment may be easily observed ; largest or adult size about 

 7-1800ths inch in diameter : 4, body-stellate, consisting of a 

 starlike spicule with conical pointed rays, united together in 

 the centre without a nucleus or body (fig. 45, e, ^), sparsely 

 scattered through the body-substance, about 3-6000ths inch 

 in diameter. Size of largest specimens, which are tuberous, 

 4 inches in diameter ; size of smallest specimens, which are 

 spheroidal, 4-12ths inch in diameter. 



Hah. ]\Iarine, free or attached to solid bodies. 



Lac. In the deep water between the north of Scotland, the 

 north-west of Shetland, and the Faroe Islands, at stations 51, 

 57, 61-63, and 65 respectively ; also near Cape St. Vincent. 



Ohs. It is difficult to find a satisfactory distinguishing 

 character among most of the Geodina, as they are so much 

 alike in all parts of the world. In the above instance this is 

 chiefly to be found in the nodose form of the surface-spicule 

 or stellate, and hence the designation ^^ nodastrella]'''' while the 

 furcate division of the arms of the zone-spicule appears to offer 

 (for the specimens dredged up on board the ' Porcupine ' at 

 least) a convenient character for separation, if not also for 

 recognizing the embryonic form of the ovum, as will presently 

 be seen. 



It was at the base of a specimen of one of these Oeodice, about 

 2 inches in diameter, that I found two projecting spicules 

 bearing respectively a globular embryonic form, which, from 

 its size, appears to be the first stage after the elimination of 

 the ovum of this species. These I mounted in balsam together, 

 on the spicules bearing them respectively as I found them. 

 One, the largest, is 14-, and the other 9-1800ths inch in 

 diameter. They are both composed of furcate zone-spicules, 

 which have the furcated arms of their heads incurvated over 

 the convexity of the embryo, while their shafts are directed 

 towards the centre; in both, too, the sarcode is sparsely charged 

 with minute stellates, from some of which the siliceous balls 

 might subsequently have become developed, as the latter ori- 

 ginate in this way, while when fully developed the siliceous 

 ball is nearly as large as the whole embryo itself. Besides 

 these spicules, the smaller specimen possesses the acerate body- 

 spicule, which projects a little beyond the surface; and one or 



