139 



PLATE LV. 



ISODICTYA DISSIMILIS, Bowerbauk. 



Vol. ii, p. 318, ' Mon. Brit. Spongiadae.' 



\&. 1. The type-specimen in the cabinet of the 

 Rev. A. M. Norman. Natural size. 



Fig. 2. A spiculum, from the primary lines of the 

 skeleton. X 250 linear. 



Fig. 3. A spiculum, from the secondary lines of 

 the skeleton. X 250 linear. 



Since the first publication of this species I have 

 received two other specimens ; one from Mr. Win. 

 Thompson, of Weymouth, five inches high and three 

 broad, and the other from Mr. W. Saville Kent, who 

 dredged it in 1870, off Guernsey; this specimen is 

 four inches high and three broad. All the specimens 

 agree in having a short pedicel, and in the fan-like 

 disposition of its branches. The external characters 

 of the species appear to be tolerably constant and 

 reliable. 



ISODICTYA PAUPERA, Bowerbmik. 



Vol. ii, p. 328, ' Mon. Brit. Spongiadse.' 



Fig. 4. Represents four of the specimens of the 

 species received from Mrs. Griffiths, of Torquay. 

 Natural size. 



Fig. 5. One of the minute, bidentate, equi-anch orate, 

 retentive spicula, from the dermal membrane. X 530 

 linear. 



Fig. 6. A skeleton spiculum. X 250 linear. 



Fig. 7. One of the slender, fusiformi-acera^e, tension 

 spicula of the interstitial membranes. X 250 linear. 



ISODICTYA UNIFOKMIS, Bowerbank. 



Yol. ii, p. 329, ' Mon. Brit. Spongiadte.' 



Fig. 8. - -Represents the type-specimen in the 

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



Fig. 9. One of the tension spicula of the dermal 

 membrane. X 250 linear. 



Fig. 10. A skeleton spiculum. X 250 linear. 



