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 VII. 



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

 sliowing cup-like bodies or pores and vents. 



F{(/. 2. The same, small spinous curved spicule of the dermal layer aTid 

 parenchyma, magnified. Size 7-1800ths long by about l-8000th 

 inch broad. 



Fl(j. 3. The same, portion of spinous spicule more magnified, to show 

 form of spmes. 



Fi(f. 4. The same, large, smooth, straight spicule of skeleton and cup- 

 like body, magnified. Size 20-1800th8 long by about 1-OOOOth 

 inch broad. 



Fiij. 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; 

 5 6, its continuity with the dermal layer; c c, cribriform disk 

 supported on sarcodal columns, in Avhich are imbedded the 

 smooth spicules whose ends project beyond the surface ; 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 rugfe ; /, its constricted 

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

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

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

 canal between the reticulations of the sarcodal network. 



Fi<j. 6. The same, cribriform disk magnified on the same scale. Fora- 

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



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

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

 longation of dermal layer forming the sides of the chamber ; 

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

 radiate as many septa to the sides of, as there are oscula opening 

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

 oscula. 



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

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

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

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

 divisions. 



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

 in diflerent degrees of expansion and contraction respectively, 

 magnified (? diameters ; also the minute papillary elevations 

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

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

 from contraction; d, minute papillary elevations on dermal 

 surface. 



Fiy. 10. The same, portion of dermal layer, magnified, to show tlie dis- 

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



