141 



PLATE LVI. 



IsoDiCTTA NoRMANi, Bcnccrhanlc. 

 Yol. ii, p. 320, • Mon. Brit. SpongiadiB.' 



Fig. 1. — Represents a specimen of tlie species from 

 off St. Martin's Point, Guernsey, in the cabinet of the 

 Rev. A. M. Norman. Natural size. 



Fig. 2. — Represents a specimen of the sponge 

 growing amidst the roots of a large fucus from Moray 

 Frith, presented to me by the Rev. Walter Gregor, of 

 Aberdeen, a a a are the masses of the sponge. 

 Natural size. 



Fig. 3. — One of the stout, acuate spicula of the 

 skeleton. X 250 linear. 



Fig. 4. — A long slender, tension spiculum of the 

 dermal membrane. X 250 linear. 



Fig. 5.— A palmato-equi-anchorate, retentive spicu- 

 lum, from the dermal membrane, x 1000 linear. 



IsoDiCTTA PYGMEA, Bowerbank. 



Vol. ii, p. 313, ' Mon. Brit. SpongiadEe.' 



Fig. 6. — Represents the largest specimen of the 

 species that I have yet seen. It was presented to me 

 by my late friend Mr. Bean, of Scarborough. Natural 

 size. 



Figs. 7 and 8. — Two other specimens of the same 

 species from Scarborough. I have several others of 

 about the same size, which appears to be the average 

 size of the species. Natural size. 



Fig. 9. — A skeleton spiculum. X 260 linear. 



Fig. 10. — One of the slender tension spicula of the 

 interstitial membranes. X 250 linear. 



