210 Mr. W. S. Kent 07i Tetliya muricata 



the part described to assume a form very much like that of an 

 Agaric." Referring next to the types of spicula figured in 

 my plate, Dr. Bowerbank assumes that I have " fallen into 

 the error of describing some of those organs (?) that do not 

 belong to the species under consideration," and enumerates in 

 consecutive order such ones as he condemns as being derived 

 from extraneous sources. 



Dr. Bowerbank's foregoing adverse criticisms being rather 

 calculated to mislead those interested in the stracture of the 

 Spongiadte, I feel it incumbent upon myself to reply briefly 

 to them. 



In the first place I must express the most unqualified dissent 

 from Dr. Bowerbank's proposition that the specimen from which 

 my description was derived is a " mutilated " one : another 

 examj)le, accompanying the individual figured, furnished the 

 same characters ; and the same may be said of a fine series 

 obtained by Dr. Carpenter and Professor Wyville Thomson 

 during their earlier dredging expeditions to the North Atlantic 

 in H.M.S. ' Porcupine.' The last-named gentleman, singu- 

 larly enough, independently adopted th'e same specific title of 

 agariciformis for this remarkable sponge, in reference to its 

 striking contour, while at the same time he further generically 

 distinguished it by the title of Tisijihonia. 



Had Dr. Bowerbank referred to his last year's volume of the 

 ' Annals,' he would have discovered that in the January 

 number I contribute additional remarks on this same sponge, 

 discarding those spicula of the hexaradiate type objected to by 

 himself as having been derived from contact with other species, 

 and correlate it with the true Tethyadee. The question now 

 remains whether the form is identical with Dr. Bowerbank's 

 Tetliya muricata, or whether it must rank as distinct a species. 

 In the former case Dr. Bowerbank's specific title will have to 

 be expunged, as, until this last issue of the Zoological Society's 

 ' Proceedings,' no recognizable diagnosis of Tetliya inuricata 

 has been published. One or two of the spicula have been 

 figured by its author in his " Physiology of the Spongiadge '* 

 in the 'Philosophical Transactions' for 1858 and 1862, and 

 in his ' Monograph of the British Spongiadte,' published by 

 the Bay Society, these being in both places referred to Tetliya 

 muricata of his own MS. ; so vague a reference, however, is 

 totally inadequate for the purpose of establishing it as a species. 

 On the other hand, the evidence in favour of its being a well- 

 established deep-sea form, closely allied to, but possessing 

 constant characters of specific value distinct from Dr. Bower- 

 bank's T. muricata is of the most satisfactory description. 

 Both Professor Wyville Thomson's specimens and my own 



