245 



PLATE LXXIX. 



HYMEEArniA coiiONULA, Bowerhcink. 



rig. 1. — Represents the type-specimen on tlie sni'- 

 face of a small bivalve shell from Shetland. Natnral 

 size. In the cabinet of the Rev. A. M. Norman. 



Fig. 2. — A small portion of the sponge mounted in 

 Canada balsam, showing the spicula in siti!. X 250 

 linear. 



Figs. 3 and 4. — Two of the attenuato-spinulate, en- 

 tirely-spined, internal defensive spicula, exhibiting the 

 peculiar circlet of spines on the basal bulb. X 530 

 linear. 



Hymedesmia inflata, Bowerhan/c. 



Figs. 6, 6. — Two of the pebbles from Shetland, 

 having patches of the sponge upon them at a a. 

 Natural size. 



Fig. 7. — A small piece of the sponge mounted in 

 Canada balsam, exhibiting the characteristic forms and 

 mode of disposition of the acerate, entirely-spined 

 spicula of the dermal membrane. X 250 linear. 



Fig. 8. — One of the angulated, entirely-spined, acerate 

 spicula of the dermal membrane. X 530 linear. 



Hymedesjiia occulta, Boiverbaiih. 



Fig. 9. — Represents the type-specimen on the frag- 

 ment of an old Pecten shell. Natural size. In the 

 cabinet of the Rev. A. M. Noimian. 



Fig. 10. — A portion of the sponge mounted in 

 Canada balsam, exhibiting the mode of the disposition 

 of the spicula. X 250 linear. 



Fig. 11. — One of the large, tridentate, equi-auch orate, 

 retentive spicula. X 530 linear. 



