THE PORIFERA. R3 



the genera Isodictya and Chalina. Professor Herdman's 

 specimens abound with ova in an advanced state of duplicate 

 sub-division, and ciliated embryos. They were obtained in 

 July and August. 



L. M. B. C, No. 85. 7. In shore pool, Port Erin, Isle 

 of Man ; also dredged near Port Erin. 



Isodictya simulans, Bk. * 

 This is a compact form of Isodictya of pretty well marked 

 character, and, therefore, is more easily recognised than 

 many species of the genus. Its spicules are short, rather 

 stout, acerates. It is usually found of a branching growth, 

 but it is polymorphous. 



L. F. M., No. 24. 5. 73, 16. Collected at Douglas Bay. V. 



Isodictya pallida^ Bk. f 



The colour of this sponge is pale grey, or cream. Its 

 spicules are stout and very slender acerates. It is of massive 

 coating growth, and is not difficult to recognise. 



L. F. M., No. 24. 5. 73. 7. Collected at Douglas Bay. V. 



Isodictya densa, Bk. | 

 This is a massive spreading growth with stout acerate 

 spicules. 



L. F. M., No. 24. 9. 73, 2. Collected at Holyhead. V. 

 L. M. B. C, No. 85. 19. Collected at Port Erin. 



Isodictya fistulosa, Bk. § 



This is a massive form throwing up thin-walled tubes or 

 fistulffi. Its colour alive is white, with a pinkish tint. Its 

 spicules are two kinds of acerates, the one fairly stout and 

 the other very slender. 



L. F. M., No. 4. 9. 74, 10. Collected at Holyhead. V. 



* Hon. Brit. Spong.,\6\. ii., p. 308; vol. iii, pi. 51. 



f Op. cit., vol. ii, p. 297 ; vol. iii, pi. 50. 



% Op. cit., vol. ii, p. 292 ; vol. iii, pi. 50. 



§ Op. cit., vol. ii, p. 299; vol. iii, pi. 53. 



