230 



ME. S. O. "RIDLEY OJ* ALCYOT^ARIA. 



numerous. Judging by mountings made from a representative 

 of each of the two apparent varieties in external form, viz. (a) that 

 with closely aggregated lobules, and (b) that with wide spaces 

 visible on the surface, there are small corresponding differences in 

 the spiculation, e. g. the cortical spicules (no. 2) in (6) are rather 

 shorter and stouter than in (a). 



S. spinosa, Gray, is the nearest described species, judging 

 by the external characters, with which I am acquainted ; 

 but the probable type (pink var.) is brown with white pro- 

 jecting spicules. The latter are very much larger than in 

 our form, constituting conspicuous objects to the naked eye ; 

 whereas, were it not for their strong coloration, they would 

 scarcely be noticed in S. aurora. In S. Studeri, mihi, the zooids 

 are decidedly scattered, and do not concea] the cortex, as 

 here. Its coloration and short stalk readily distinguish it from 

 the other two forms described below. The difference between 

 those specimens (var. a, above) in which the lobules form a close, 

 continuous covering to the head and those (var. b) in which they 

 are separated by wide gaps, in which the bulky white axis is 

 well seen (producing a resemblance to S.florida), is instructive, 

 but leaves the arrangement of the zooids on the lobule unaffected 

 as a specific character ; it appears, though commonly obtaining 

 in young specimens, to be independent of age, as two or three 

 large specimens exhibit it. 



Spongodes boletiformis, sp. n. (Plate XVII. figs. 17-19.) 



Erect, distinctly capitate. Stem long (that of the single ex- 

 ample about 2 diameters high). Head distinct, sublobate, much 

 compressed, of rounded even outlines. From the stem arise 

 rapidly short broad fungiform lobes which break up, without 

 much intermediate division, into the very variously shaped, ex- 

 teriorly flattened, and closely appressed terminal lobules, which 

 cover evenly the entire surface in a tessellated manner ; diameter 

 of lobules at surface about 2-3 millim. 



Zooids arising by short distinct stalks (apparently about *18- 

 *8 millim. long) from the lobule; crowded at surface, almost 

 all attaining tlx; same level, about "7 millim. in horizontal 

 diameter in closed state. Lobule surrounded by the " projecting 

 spicules" of the peripheral zooids, which accompany the latter to 

 the number of I to 3 each ; they rise but slightly (about -3 millim.) 

 above the burfaco of the lobule. 



