257 



PLATE LXXXI. 



NoEMANiA, Boiverhank. 



Fig. 1. — Represents tlie type-specimen of Normania 

 crassa of the natural size. 



Fig. 2. — A small portion of a section of the sponge at 

 right angles to its surface, exhibiting the irregularity of 

 the structm^e of the fasciculi of the skeleton and of their 

 mode of disposition. X 25 linear 



Pig. 3. — A portion of dermal inhalent surface from 

 the exterior of the sponge, showing the " short fasci- 

 culi of siliceous spicula" and the disposition of the 

 inhalent pores. X 36 linear. 



Fig. 4. — A sub-fusiformi, acerate skeleton spiculum. 

 X 80 linear. 



Fig. 5. — An expando-ternate connecting spiculum 

 of the normal form, with a very short shaft. X 80 

 linear. 



Figs. 6, 7, and 8. — Three of the various abnormal 

 forms of the connecting spicula, usually found irre- 

 gularly dispersed a short distance beneath the dermal 

 membranes. X 80 linear. 



Fig. 9. — One of the small sub-fusiformi acerate 

 tension spicula of the interstitial membranes. X 80 

 linear. 



Figs. 10 and 11. — Two of the large attenuate -stel- 

 late, retentive spicula. X 250 linear. These spicula 

 agree with each other very nearly in size but not in 

 the number of their radii. 



Fig. 12. — One of the small elongo-attenuato-stellate, 

 retentive spicula. X 260 linear. 



17 



