dredged up from the Gulf of Manaar. 371 



that the two are very nearly allied in form ; and as no flesh- 

 spicules were formerly found with Tlioosa socialis, it is not 

 improbable that one is but a variety of the other. The scep- 

 trellum, however, althouc-h alike in form, is more than twice 

 the size of that in Alectona Higgini, while the Imear spicule 

 is not so long. The " bit of film " examined having had no 

 direct connexion with the rest of the sponge lining the cavity, 

 is proof that these sponge-spicules formed imrt of the spicu- 

 latiou of Tlioosa socialis, and were not accidental occurrences. 



Stelletta crassicula, n. sp. 



Globular, firm. Colour brown-grey. Surface even, areo- 

 lar, formed by the spreading heads of the bundles of zone- 

 spicules, through which those of the anchoring-spicules 

 project, tympanized in the intervals by the dermal sarcode. 

 Pores in the dermal sarcode. Vents single, scattered here 

 and there. Internal structure, as usual, hard and tough ; the 

 bundles of zone- and body-spicules extending nearly to the 

 centre, as they are large and the specimen very small. Spicules 

 of six forms, viz. four skeleton- and two flesh-spicules. 

 Skeleton-spicules : — 1 , zone-spicule trifid, arms spreading 

 laterally, slightly extending forwards, and recurved, shaft 

 long and smooth, gradually sharp-pointed, head l-360th inch 

 in diameter, shaft l-9th inch long; 2, body-spicule large, 

 acerate, curved, fusiform, gradually sharp-pointed, smooth, 

 l-9th inch long ; 3 and 4, anchor and fork, head of largest 

 anchor about l-150th inch in diameter, shaft variable, l-9th 

 inch long or more. Flesh-spicules : — 5, minute acerate, thin, 

 curved, fusiform, gradually sharp-pointed, smooth, about 

 l-80th inch long ; 6, stellate, as usual minute, delicate, with 

 a variable number of straight arms radiating directly from the 

 centre without nucleus, about l-3000th inch in diameter. 

 Nos. 1-4 are in bundles, the anchors and forks projecting a little 

 beyond the surface, and the flesh-spicules chiefly confined to 

 the dermal sarcode. Size \ inch in diameter. 



Hah. Marine. On a Melobesian nodule, attached by the 

 anchoring-spicules. 



Loc. Basse Ilocks. 



Ohs. The smallness of this specimen compared "with the 

 large size of its skeleton and anchoring-spiculation, especially 

 the projecting heads of the anchors, at once characterizes it ; 

 but when the dermal acerate flesh-spicule is added, the dis- 

 tinction of the species becomes complete so far, since I do not 

 know another instance in which the dermal flesh-spicule is 

 at the same time smooth and so large. 



