1868.] DR. J. S. BOWEUBANK ON SPONGES. 131 



having previously disposed of the latter as Bonatia aurantium, page 

 5-1 1, in accordance with the views of Nardo, My two species, Mon. 

 Brit. Spou. vol. ii. pp. SI & 89, are converted into Collingsias ; and 

 Tethea nmricata, of which he knows nothing, but the form of one 

 sort of retentive spiculum, he transforms into Thenea miiricata. Tethea 

 rohusta and T. inijaUi, of which he knows nothing but the figures of 

 a spiculum of each represented by figures 164 & 16o, plate 6. vol. i. 

 Mon. Brit. Spon., he at once consigns to the rejected genus Cy- 

 donium, Fleming, resuscitated by Dr. Gray to be thus filled by his 

 fertile imagination Avith species. 



Dr. Gray thus disperses the species of one of the most striking 

 genera with which we are acquainted among sponges — so much so that 

 the student who has become acquainted with one species can scarcely 

 fail at the first glance to assign any others he may acquire to their 

 proper genus in existing arrangements. 



The author has arranged the Geodiadce in his Order VI. Sphte- 

 rospongia, page 547. In the definition of this order he has two 

 names for the same organ in one sentence. In place of ovarium 

 he has first ovisac-cells and then ova-cells ; and in his description of 

 the family Geodiadce, immediately following, there is a third varia- 

 tion, ovisacs. 



Instead of placing the type genus of the family, Geodia, Lamarck, 

 first, he gives that position to my genus Pachijmatisma, decidedly 

 an aberrant one, and places Geodia second. He then separates all 

 the species of Geodia described by Prof. O. Schmidt and by me, and 

 places them under the very doubtful genus Qijdonium, Fleming, pao-e 

 548, thus— "2. Cijdonium muelleri [mUlleri], Fleming, B. Ar516°" 

 in which Dr. Fleming describes his genus as having " polypi with 

 a central opening and an orifice at the base of each of the eight pin- 

 nated ten taenia," — showing either that he had greatly mistaken the 

 nature of Geodia zetlandica, Johnston, or that he had described the 

 orange-coloured variety of Jlci/onium digitatum, Johnston's ' British 

 Zoophytes,' 2nded. vol. i. p. 174. The latter appears to be the 

 most probable. 



Dr. Gray then, to increase the confusion, adds to the genus Oy- 

 donium Tethea ingalli and T. rohusta, from the figures of spicula 

 only from each quoted by me in ' Monograph of British Spongiadce,' 

 vol. i. pi. 6. figs. 164 & 165, leaving Lamarck's genus Geodia to 

 be represented by the type species, G. gihherosa, and one other, 

 G. caribea, Duchass. et Michel. I have had the opportunity of 

 carefully examining Lamarck's type specimen in the Jardin des 

 Plantes, Paris, and am well acquainted with its organic structure ; and 

 I will venture to say that no practical naturalist who has had the 

 like advantage and was acquainted with the other well-known species 

 of Geodia would for one moment dream of separating them from 

 Lamarck's genus. To complete the confusion of ideas, we then have 

 a specimen of Pachymatisma, P. listeri, on the faith of the fornt 

 of one spiculum, figs. 50 & 51, pi. 2, Mon. Brit. Spong., transformed 

 into a new genus, I'riate, page 549 of the author's paper, and, by the 

 same uncertain means, identified with Prof. O. Schmidt's Stelletta 



