Prof. E. R. Lankester's Rejoinder to Prof. Claus. 179 



manner ; and not only this, but, what is very remarkable, the 

 axial canals are at the same time preserved. Manzoui be- 

 lieved that these axial canals, appearing isolatedly in thin 

 sections without the trabeculaj belonging to them, originally 

 existed in flattened dilatations, which were produced by 

 closure of the mesh-spaces, and consequent coalescence of the 

 skeletal trains lying in the same plane, such as occur especi- 

 ally in the dermal layers in the Hexactinellidffi. I cannot 

 adopt this notion ; but after examination of such sponges from 

 Bologna I rather believe that I can prove that the trabecula 

 belonging to each of these axial canals originally existed 

 distinctly, and not amalgamated with the laterally con- 

 tiguous ones, but separated in the regular way from the latter 

 by the meshes, and that the remarkable phenomenon now 

 presented to us is merely a consequence of the process of 

 fossilization. 



The absolute proof of this, as indeed of the originally sili- 

 ceous composition of the hollow skeleton in Astylospongia, 

 Aulocopium, liindia^ &c., requires the coherent exposition of 

 a whole series of observations, with the considerations arising 

 from them, and would go beyond the purpose and limits of 

 these communications ; I may therefore be excused for touch- 

 ing upon this point quite lightly in this place. 



As a result, we are justitied in concluding from the preced- 

 ing statements that Hindia fibrosa is no doubtful form, not 

 belonging at all to the sponges, as Prof. Steinmann thought 

 he was obliged to assume, but a well-characterized, true tetra- 

 cladine siliceous sponge. 



XIX. — Professor Claus : a Rejoinder. 

 By Prof. E. Ray Lankester, M.A., LL.D., F.R.S. 



It is necessary that I should say a few words in criticism of 

 Prof. Claus's attempt in this Magazine (July 1886, p. 55) to 

 justify the statements previously made by him and objected 

 to by me. Professor Claus has chosen to call the charges 

 made against him by me " frivolous." Were I to indulge in 

 the use of descriptive adjectives I should feel obliged to use a 

 somewhat stronger one in reference to his defence of his pro- 

 ceedings. I will, however, merely say that it has not sur- 

 prised me, and that no one who is acquainted with the history 

 of certain discussions between Prof. Claus and Prof. Weiss- 

 mann, or again of a similar discussion between Prof, Claus 



