Spdngia stiberia, 491 



magnified, appear ocellated : towards the tail are three short 

 white processes placed in a line across the back, which are 

 not retractile ; and there are eighteen short obtuse branchial 

 processes placed on the margins, the smallest in front, and 

 all tipped with orange ; the apices, perhaps, conformed like 

 suckers : foot oblong, with plain margins : aperture of gene- 

 ration lateral and anterior. 



When viewed through a magnifier, this pretty mollusc has 

 a roughish or flocculent appearance. The cloak contains 

 numerous calcareous spicula interlaced in every direction, the 

 spicula of unequal sizes, curved, with a sort of knob in the 

 centre, whence it tapers to each end, the points of some of 

 them being forked. The latter sort are abundant in the 

 branchial processes, and the forked end is always pointed 

 outwards. 



The specific character may be thus expressed : — 

 Tergipes 'pulcher\ Corpore ovato, albo, supra tuberculis coc- 



cineis notato ; tentaculis duobus, ovatis, imbricatis, aurantiis ; 



branchiis brevibus, apice aurantiis. 



23. ? 5po'ngia sube^ria. {fig. 60.) 

 Our figures of this remarkable production are taken from 

 a dried specimen, with the loan of which I was favoured by 

 Mr. Bean of Scarborough. It incrusts a univalve shell, 



60 



5p6ngia sub^ria, of the natural size. 



apparently the Turbo crassior, and entirely covers it. The 

 zoophytical crust is thin and uniform, and no pores or faecal 

 orifices are visible on the surface, but the processes are hollow, 

 and their walls, which are smooth and alike on both surfaces, 

 appear to be perforated, in a longitudinal direction, with a 

 circle of small canals which probably open on the rim of the 

 process ; but this structure is rather inferred from the appear- 

 ance presented by the spot from which a process has been 

 broken, and from an obscure vestige of pores on the rim, than 

 from dissection, and remains, therefore, open to correction. 



The sponge is apparently composed of fine particles of sand 

 closely compacted, and is of a uniform grey or stone colour ; 

 the surface is even and smooth, but large papillary processes, 

 from one to six lines in height, cylindrical and tubular, rise up 

 irregularly from it, the apices of which are circular, cupped. 



