368 Contributions to our Knowledge of the Spongida. 



EXPLANATION OF THE PLATES. 



KB.— All tie figures, except the " more magnified " flesh-spicules, are 

 drawn to the scale of l-24th to 1 -1800th inch, in order that their relative 

 sizes may at once be recognized. The " more magnified" views are 

 chiefly on the scale of l-24th to l-6000tk inch. 



In Plate XV. the spiculation of Tethya merguiensisis drawn to the scale 

 of l-48th to l-1800th inch, as the limits of the Plate would not permit 

 of their being delineated upon that of the preceding Plate, viz. l-24th to 



1 -1800th inch. 



Plate XIV. 



Fig.l. Geodia canaliculata, Sdt, spiculation of. Skeleton-spiculea : a, 



body -spicule ; b, zone-spicule; c, anchor, with part of shaft. 

 (Where anchors and forks are not given together, it must not be 

 inferred that the missing one or both were not present, but rather 

 that they were not seen.) Flesb-^picules : c/, siliceous body or 

 ball ; e, abnormal form of the same ; f } stellate ; g 9 dermal acerat". 

 Scale l-24th to l-1800th inch. More magnified views : A, 

 siliceous body or ball; i, surface-pattern of the same, still more 

 magnified, upper view; k, the same, lateral view; /, abnormal 

 forms of siliceous ball ; m f stellate. A, /, and m are to the scale 

 of l-24th to 1 -6000th inch, and i and h to a still larger scale. 



Fig. 2. Stelletta au&tralimsis, n. sp., spiculation of. Skeleton-spicules : a y 



body-spicule ; 6, zone-.-pieule ; c, anchor ; d, fort. Flesh- 

 spicule.-, : e, bacillar body ; /, stellate, y, fragment magnified 

 2 diameters, to show thinness of A, the crust or cutis. 



Fig. 3. Stelletta bacilli/era, var. robust a, n. var., spiculation of. Skeletal 



spicules : a, body-spicule ; 6, zone-spicule ; c, anchor. Flesh- 

 spicules : d, bacilliform body ; e, stellate ; f, dermal acerate. 



More magnified views : g, bacilliform body ; h, stellate ; s i i, 

 abnormal forms of g. 



Fig, 4. Stelletta reticulata, n. sp., spiculation of. Skeletal spicules : a, 



body-spicule ; b, zone-spicule (no anchors or forks seen). 

 Flesh -spicules: c, globostellate, with rays truncated and spined; 

 dj stellate. More magnified views : e, globostellate ; /, stellate. 



Fig. 5. Stelletta globostellata, n. sp., spiculation of. Skeletal spicules: 



a, body-spicule; b, zone-spicule (anchors and forks not seen) ; 

 c, globostellate with rays pointed and smooth ; d, internal stel- 

 late. More magnified views: e, globostellate;/, internal stel- 

 late, g, fragment magnified 2 diameters, to show thickness of 

 A, the crust or cutis, 



Plate XV. 



Fig. 6. Tethya mergviensis, n. sp., natural size, a, upper view; A, vents ; 



c, lower view ; d, base of attachment ; e, lateral view ; /, base 

 of attachment. 



Fig t 7. The same, spiculation of. Skeleton-spicules : a, body-spicule; 



b b, zone-spicule ; c, anchor ; rf, fork. Flesh-spicules : f, Mba- 



mate ; g, dermal acerate. e, real length of bodv-spicu)e. More 



magnified views: A, bihamate or fibula; •, pigmental cells; 



&, pigmental cell still more magnified, to show the pigment- 

 granules. 



Fig. 8. The same. Interstice of dermal fibro-reticulation, much but rekh 



tirely magnified, to Fhow the elements of the dermis, aaaaaa, 



