66 On new and remarkable Species of Cliona. 
fice of its spines, a great length (0-0033 inch) relative to its 
breadth, which is too small for measurement, and remains 
smooth. 
This must be regarded as a variety of C. celata ; and I pro- 
pose for it the name of C. linearis. 
Cliona linearis, var. of C. celata. 
Skeleton-spicule as in C. celata (fig. 2,a). Flesh-spicule a 
long filiform acerate (fig. 2, e), straight or tricurved; length 
0:0033 inch, breadth so narrow as scarcely to exhibit a double 
outline under a magnification of 500 diameters. 
EXPLANATION OF THE PLATES. 
PraTtE I. 
Fig. 1. A fragment of Ists, sp., with Cliona-burrows : m,m, chambers of 
C. mucronata; e, e', of C. ensifera (natural size). 
Figs. 2-7. Outlines of chambers (A, B, C) of C. mucronata, showing 
various forms of diaphragms (a, }, c, d,d,, d,, d,): d', diaphragm 
seen in plan, concealing an aperture beneath it; w, walls of a 
chamber. x 30. 
Fig. 8. Hemispherical pittings on the walls of the Clhona-burrows. 
x 60 
Fig. 9. Imperforate conical form of diaphragm (C mucronata), seen from 
its convex or exterior surface. X 30. 
Fig. 10. Tubular diaphragms (C mucronata): f, film of dried sarcode 
containing spicules; 7, lumen. x 380. 
Figs. 11-13, Diaphragms of C. ensifera: f, film of attached membrane; 
ce, cells contained in the membrane. xX 30. 
Fig. 14. View of the edge of a diaphragm of C. mucronata. x 140. 
Fig. 15, Superficial view of the inner surface of a diaphragm of C. mucro- 
nata mounted in Canada balsam. x 140. 
Fig. 16. Openings in the walls of chambers of Cliona leading into tubular 
processes. X 50. 
Fig. 17. Openings on the exterior of the Cliona-containing Isis, leading 
into the chambers of C. mucronata within: p, openings for pores; 
o, for oscules? xX 30. 
Fig. 18. Cells from the membranous films found in the chambers of C. 
ensifera: b, vacuole. X 4365. 
Puate II. 
[All the figures on this Plate are magnified 435 diameters. ] 
Figs. 1-9. ‘Cliona mucronata. 
Figs, 1-3, mucronate spicules; figs. 4 and 5, varieties of the preceding ; 
figs. 6 and 7, slender acuate spicules; fig. 8, variety of figs. 6 
and 7, having two shafts, a short cylindrical one with rounded 
ends and a slender pointed one, both proceeding from the same 
head; fig. 9, various forms of flesh-spicules. 
Figs. 10-25. Chona ensifera. 
. Figs. 10, 11, and 22, normal ensiform spicules exhibiting different degrees 
of curvature. 
