a new Genus and Species of Sponges. 197 



has the power of opening and closing itself as occasion may 

 require (figs. 7, 8). 



EXPLANATION OF PLATE VIL 



Fig. 1. Grayella cyathophora, n. sp., magnified twice the natural size ; 

 showing cup-like bodies or pores and vents. 



Fiy. 2. The same, small spinous curved spicule of the dermal layer and 

 parenchyma, magnified. Size 7-1800ths long by about l-8(X)0th 

 inch broad. 



Fig. 3. The same, portion of spinous spicule more magnified, to show 

 form of spines. 



Fig. 4. The same, large, smooth, straight spicule of skeleton and cup- 

 like body, magnified. Size 20-1800ths long by about l-6000th 

 inch broad. 



Fig. 5. The same, vertical section of one of the cup-like bodies, greatly 

 magnified (scale l-48th to l-1800th of an inch) : a a, cup ; 

 b h, its continuity vnth the dermal layer ; c c, cribriform disk 

 supported on sarcodal columns, in which are imbedded the 

 smooth spicules whose ends project beyond the siu:face ; d, por- 

 tion of cribriform disk covering the cavity or central chamber 

 of the cup ; e, vertical section of funnel-shaped prolongation of 

 central chamber, showing its circular rugae ; /, its constricted 

 end opening into r/, the commencement of an excretory canal ; 

 h, reticulated sarcodal rugse, characteristic of the internal sur- 

 face of the excretory canals ; i, apertures opening into excretory 

 canal between the reticulations of the sarcodal network. 

 'Fig. 6. The same, cribriform disk magnified on the same scale. Fora- 

 mina varying from 1-1800 to l-300th of an inch in diameter. 



Fig. 7. The same, vertical section of vent, greatly magnified and dia- 

 grammatic, to show : — a, opening of cloacal chamber ; b, pro- 

 longation of dermal layer forming the sides of the chamber; 

 c, papillary eminence in the centre of the chamber, from which 

 radiate as many septa to the sides of, as there ai'e oscula opening 

 into, the chamber; d, d, portions of chamber leading down to 

 oscula. 



Fig. 8. The same, horizontal section of vent, gi-eatly magnified and dia- 

 grammatic, to show : — rt, external surface of dermal prolongation 

 forming cloacal chamber; b, cut edge of same; c,c,c,c, openings 

 of oscula ; d, horizontal section of papillary eminence and septal 

 divisions. 



Fig. 9. The same, portion of dermal layer, to show three cup-like bodies 

 in difterent degrees of expansion and contraction respectively, 

 magnified G diameters ; also the minute papillary elevations 

 between them : a, fully expanded cup ; 6, half-expanded cup ; 

 c, wholly contracted cup, showing its ribbed coral-like form 

 from contraction; d, minute papillary elevations on dermal 

 siu-face. 



Fig. 10. The same, portion of dermal layer, magnified, to show the dis- 

 position of the small spinous spicules with which it is charged. 



