1868.] DR. J. S. BOWERBANK ON SPONGES. 125 



I have before stated, in treating of subsection 2, that Euplectella, 

 Owen, is not a spiculo-reticulate sponge, but truly a siliceo-fibrous 

 one ; but under the head of Dr. Gray's order 4 it will take its place 

 very well, as among its auxiliary spicula it certainly has " spicules 

 of more than one form or kind." This, however, is rather a loose 

 way of disposing of it, and totally ignores the most essential part 

 of its structure, the skeleton. 



Order V. Arenospongia is formed by the conversion of the author's 

 genus Xenospongia into an order. The specimen is in the British 

 Museum, and is described in the Proc. Zool. Soc. for 1858, p. 320. 



Section II. p. 504. Chlamydosporce. What the author means by 

 "sponges with armed spores" it is difficult to imagine, unless it 

 be meant to intimate that sponges are vegetable bodies ; but as he 

 combines the term spore with that of ovisac, it is probably only an 

 error in his terminology; and this is very likely to be the case, as in 

 order VI. Spharosponyia, immediately following, he describes the 

 "ovisac" as emitting ova. The ovaria or "ovisacs" are occasion- 

 ally armed or constructed with spicula ; but the ova, or spores, have 

 never yet been found to contain them. 



Order VI. Sphcerospongia. Both of the author's families Geo- 

 diadce and Placospongiadce are misplaced in this order, as the 

 ovaries or " ovisacs," as I have before stated, are in neither case 

 armed, the external surfaces of the adult bodies being perfectly 

 smooth in every species with which I am acquainted. 



Order VII. (p. 504) is based on the structural peculiarities of 

 the ovaria of the genus Spongilla ; but, from the author's vague de- 

 scriptions of their structures, both " Tethya'' and Geodia would 

 be as naturally referred to this order as to order 6. 



The Families. 



The families comprised in the seven orders are eighteen in num- 

 ber ; they are simply based on the genera established in the works 

 of Dr. O. Schmidt, the ' Monograph of British Spongiadse,' and a few 

 other authors, including those of Dr. Gray, the characters of the 

 genera being taken by the author and generally altered in the manner 

 of description, but certainly not with the effect of rendering them 

 more definitive or distinctive. I will not discuss their merits seriatim, 

 but notice those only in which the errors are of a striking character. 



Family 1. Dactylocalycidce, p. 502. In consequence of the in- 

 accuracy of the description of order I. Coral liospongia, which is 

 stated to be " entirely formed of siliceous spicula anchylosed toge- 

 ther," the family the members of which are siliceo-fibrous, and 

 not spicular, in their skeleton-structures, appears to be entirely 

 misplaced. The author's description of his order should therefore 

 be amended to remedy this discrepancy, or the family removed to 

 another order. 



Family 7. Ophistospongiadce, p. 503. This term is an error in 

 spelling, as it is derived from my genus Ophlitaspongia, Mon. 

 Brit. Sponges, vol. ii. p. 14. 



