sponges from the Atlantic Ocean. All 



Plate XIV. 



Fig, 20. Cometella pyrula, n. sp., on a pebble, a a, two pebbles linked 

 together by the stem of another specimen, from which the head 

 has been broken off; b, C. injrula ; c, stem without head : natu- 

 ral size, d, section of the same, magnified two diameters, to 

 show internal structure, composed of nucleus with radiating 

 bundles of spicules, ovarian zone, layer of compressed excre- 

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

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

 y, thereon is surrounded bj' a bundle of long acerate spicules 

 like i, and the surl'ace (j, covered with polygonal 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, " ^," about which the auchorate spicules, 

 " Z," are congregated and alone to be found ; i, skeleton-spicule ; 

 h, spined acuate or subskeleton-spicule : /, anchorate ; in, the 

 same, more magnified : 7.-, /, i are drawn to the same scale, viz. 

 l-48th to l-6000th inch. For the skeleton-spicule see also 

 PI. XV. fig. 38. 



Tig. 21. Hymeraphia verticillata, Bk., on a pebble, magnified two dia- 

 meters, a, pebble ; b, H. verticillata ; c, monticules, from which 

 respectively a large skeleton-spicule projects as at "??i;" d, fixed 

 end of large skeleton- spicide, often bulbous ; e, acerate centro- 

 infiated spicule, fissurate at the ends ; /, central inflation ; 

 g g, fissurate ends; h, the same, magnified, to show the three 

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

 spined; k, the same, moniliform ; /, the same at an early stage 

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

 m, diagram of monticule, to show its elementary composition 

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

 layer charged with verticillate and moniliform spicules ; o o, 

 group of centrally inflated spicules surrounding the great acuate 

 spicule^. For the skeleton-spicules see PI. XV. fig. 39, a, b. 

 d, e, i, and h are on the same scale, viz. l-48th to l-6000th 

 inch. 



Fig. 22. Pachastrella amygdaloides, on a piece of rock, natural size, a, rock ; 

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

 natural size, c, rock ; f, sponge ; g g, forms of large radiate 

 skeleton-spicule ; h, form of acerate spicule ; i, subskeleton- 

 spicvde, microspined ; k, flesh-spicule, microspined ; / /, stellate 

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

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



Fig. 23. Pachastrella geodioides, natural size : a, diagram on the scale of 1- 

 48th to 1-I800th inch, to show heterogeneous composition of 

 body and surface ; bbb, large radiate skeleton-spicules ; ccc, 

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

 balls of a Geodia ; f, test of a Glvbigerina ; g g, grains of quartz ; 

 h, dots representing globo-tuberculated stellates, more magnified 

 in m. Spicules separate : — «", large radiate skeleton-spicule, 

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

 cules of various forms ; /, acerate spicule, scale l-24th to 

 l-CiOOOth inch ; 7n, globostellate or flesli-spicule under its two 

 forms, viz. ?«, with stelliform interior, o, with solid interior, scale 

 l-12th to l-6000th inch; p, more magnified view of tubercle. 

 N.B. As the skeleton acerate spicule is of the same form in 



