New Species of Excavating Sponge, dtc. By H. J. Carter. 497 



• Gen. 2. Thoosa, Hancock, 1849. 



Form of skeleton-spicule undetermined (? '• multifid "). Flesh- 

 spicule nodular, consisting of a stout shaft, terminated at each 

 extremity by a globular inflation, and encircled by two rings of 

 similar inflations equidistant from the extremities respectively and 

 from each other.* 



Gen. 3. Alectona, Crtr., 1879. 



Skeleton-spicule acerate, abruptly curved or bent in the centre, 

 tubercled throughout, Flesh-spicule spindle-like, consisting of a 

 straight shaft, pointed at the extremities and encircled by two 

 rings of tubercles equidistant from each other and from the ends 

 of the shaft respectively, t 



It is not improbable that Samus anonyma X may have to 

 come in as a fourth genus. 



Lastly, I would observe, with reference to Aleetona Millari, 

 that on one part of the specimen of AmpTiihelia was an irregular 

 mass about two lines in diameter horizontally, and ^V inch 

 high, opaque and cream-coloured, looking very much like a bit of 

 Alcyonium, especially from the form of its spicules when viewed 

 under the Microscope, but which, on the application of acid, proved 

 to be entirely siliceous and identical in spiculation with A. Millari. 

 Thus, A. Millari, like Cliona celata, may leave its burrows and 

 grow up externally into a massive form. 



The papilla, too, may be represented by a solid mass or plug 

 of spicules, when it appears to have become effete, and the whole mass 

 externally, composed of sarcode charged with spicules of the species 

 mixed with, and finally faced by foreign material, i. e. quartz-sand, 

 with a slight admixture of carbonate of lime, which causes it to 

 effervesce under the influence of acid ; thus entirely devoid of pores 

 or passages. 



Rhaphidotheca, Kent, 1870. 

 (' Ann. and Mag. Nat. History,' vol. vi. p. 222, pi. xv.) 



Rhaphidotheca affinis, n. sp. 



Another sponge found and recognized by Dr. Millar upon this 

 specimen of Aynphihelia oculata is similar to that described and 

 illustrated by Mr. Saville Kent,§ which came from a specimen of a 

 like kind, viz. Lophohelia prolifera ; that is, it consists of an 



* See Hancock's figure and description, ' Ann. and Mag. Nat. History,* 1849, 

 vol. iii. p. 346, pi. xii. figs. 2, &c. ; also ibid., 1879, vol. iii. pi. xxix. fig. 21. 

 t Ibid, ih., p. 353, pi. xxix. figs. 5-9, Corticimn, now Alectona Wallichii. 

 X Ibid, ib., I. c. p. 350, pi. xlix. fig. 1, &c. § Op. et I. c. 



