sponges from the Atlantic Ocean. 477 



Plate XIV. 



Fii/. 20. CdinrtcUa pyrtda,n. sp., on a pebble, a a, two pebbles linlced 

 td^a'tlier bv tlie A^m. of another .specimen, from which tlie head 

 has been broken oil"; h, C. pijnila; c, stem without head: natu- 

 ral size, r/, section of the yame, niafrnilied two diameters, to 

 show internal structure, composed of micleus with radiatin}^ 

 bundles of spicules, ovarian zone, layer of compressed e.vcre- 

 tory cavities, subdermal zone, and dermal layer, diagrammatic. 

 e, summit, still more uiatruitied, to show that the terminal vent, 

 /, thereon is surrounded by a bundle of long acerate spicules 

 like i, and the surface //, covered with polygonjd spaces, whose 

 lineation culminates in pointed elevations; //, elevation, greatly 

 magnified, to show that it is a pore situated in the centre of a 

 whirl of the spicules, " /o," about which the auchorate spicules, 

 " l," are congregated and alone to be found ; i, skeletou-spicule ; 

 k, spined acuate or subskeleton-spicule : /, anchorate ; ?«, the 

 same, more magnified : h; I, i are drawn to the same scale, viz, 

 l-48th to 1-GOOOth inch. For the skeleton-spicule see also 

 PL XV. tig. ;j8. 



Fig. 21. Hymeniplna vertkiUuta, Bk., on a pebble, magnified two dia- 

 meters, ff, pebble ; h, H. verticillata ; c, monticules, from which 

 respectively^ large skeletou-spicule projects as at "?«;" (/, fixed 

 end of large skeleton-spicule, often bulbous ; c, acerate centro- 

 intlated spicide, fissurate at the ends ; /", central inflation ; 

 y (jf iissurate ends; h, the same, magnified, to show the three 

 arms ; /, staple spicule of the body and dermis verticillately 

 spined; A-, the same, moniliform ; /, the same at an early stage 

 of development, to show that the bead-like form is persistent ; 

 ?/i, diagram of monticule, to show its elementary composition 

 and the arrangement of the spicules composing it ; n, dermal 

 layer charged with \ erticillate and moniliform spicules ; o o, 

 group of centrally inflated spicules surrounding the great acuate 

 spicule p. For the skeletou-spicules see PI. XV. fig. 39, a, 6. 

 d, e, i, and k are on the same scale, viz. l-48tii to 1-COOOth 

 inch. 



Fiy. 22. PuchadreUa anujydaloides, on a piece of rock, natural size, a, rock ; 

 h, sponge ; c, vent-area ; d, the same specimen, lateral view, 

 natm-al size, e, rock ; f, sponge ; y y, forms of large radiate 

 skeleton-spicule ; /(, form of acerate sjicule ; i, subskeleton- 

 spicule, microspined ; k, fiesh-spicule, microspined ; //, stellate 

 with linear arms or rays : with the exception of h and /, all are 

 on the same scale, viz. l-24th to l-COOOth inch. 



Fiy. 23. PachaMn-llu ycddiuidcs, natural size : a, diagram on the scale of 1- 

 48th to l-L'UOth inch, to show heterogeneous composition of 

 body and surface; iii, large radiate skeleton-spicules; c c c, 

 subskeleton radiate spicules ; d d, acerate spicules; ee, siliceous 

 balls of a Giodia ; f, test of a Ghbiycrinu ; // y, giaius of quartz ; 

 h, dots representing globo-tuberculated stellates, moie magnified 

 in m. Spicules separate : — /, large radiate skeleton-spicide, 

 with three arms, on same scale ; A; A; A, subskeleton radiate spi- 

 cules of various forms ; /, acerate spicule, scale l-l'4th to 

 l-( 000th inch ; m, globostellate or flesh-spicule under its two 

 forms, viz. «,with stellifurm interior, <>, with solid interior, scale 

 1-1 2th to l-('000th inch; ;?, more magnified view of tubercle. 

 X.li. As the skeleton acerate spicule is of the same form in 



