Sponges from the Atlantic Ocean. 399 



flattened sides respectively, composed of radiating, columnar 

 stnicturc intcnially, oacli jiillar emlin^ on the surface in a 

 littK' stc'ilifonn lifa<l, wliicli, in juxtaposition, ])roduccs the 

 tcssollatt'd 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 

 stati'd, ill all stajj^es of growth, where their gradationary deve- 

 lopment may be easily observed ; largest or adult size about 

 7-lSOOths inch in dianu'ter : 4, body-stellate, consisting of a 

 starlike spicule with conical pointed rays, united together in 

 the centre icithout a nucleus or body (ttg. 45, e, i), sparsely 

 scattered through the body-substance, about 3-600()ths inch 

 in diameter. 8ize of largest specimens, which are tuberous, 

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

 spheroidal, 4-12ths inch in diameter. 



llab. ]Marine, free or attached to solid bodies. 



Loc. 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 ditiicult to tind 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 suiface-spicule 

 or stellate, and hence the designation "no^as/re/Za;" while the 

 furcate division of the anns 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 tlie embryonic form of the ovum, as will presently 

 be seen. 



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

 2 inches in diameter, that I found two projecting spicules 

 bearing resjiectively a globular embryonic form, wliich, from 

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

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

 on the spicules bearing them res])ectively as I found them. 

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

 diameter. Tliey 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 subscfpiently 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 s])ecimen possesses the acerate lx)dy- 

 spicule, which projects a little beyond the siu-face; and one or 



