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PLATE LXXIX. 



HTMEEAPHIA COEONULA, Bowerbank. 



Fig. 1. Represents the type-specimen on the sur- 

 face of a small bivalve shell from Shetland. Natural 

 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 situ. 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, Bowerbank. 



Figs. 5, 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. 



HYMEDESMTA OCCULTA, Bowerbanh. 



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. Norman. 



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-anchorate, 

 retentive spicula. X 530 linear, 



