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Show 384 PROF. E. A. MINCHIN ON THE BRITISH [Dec. 13, Leuconia somesii; why he should have called these specimens Leuconia is a mystery to me. Haeckel gave the species the name variabilis on account of " the unlimited changeableness of its form as a whole, as well as of its specific skeleton-structure." I have already expressed my opinion upon Haeckel's figures of the external form ; as regards the spicu-lation, L. variabilis is variable certainly, but not more so than other Ascons. The frequent association, mentioned above, of this species with a heterocoele sponge, and the constant contamination, so to speak, of spicule-preparations of the Ascon by spicules not properly belonging to it, may account for Haeckel's noticing in this instance the variability of the spiculation. Haeckel described variabilis as having two kinds of monaxons, small and large; but from his figure it is evident that the smaller kind seen by him were the small curved monaxons, and he did not notice that they are connected by every possible gradation of size with the large ones. He overlooked the small straight monaxons, as I must also confess to have done till quite recently. Haeckel made four specific varieties-cervicornis, confervicola, arachnoides, and hispidissirna,-based on variations of the relative numbers of the different sorts of spicules, and leading up to his so-called " connexive varieties," distinguished, in his usual way, by ringing the changes on the generic name, such as Ascaltis, Ascortis, Asculmis, or Ascyssa variabilis. None of these varieties appears to me to have any taxonomic value except hispidissirna, which might be retained for forms such as were named by Bowerbank Leuconia somesii: i. e. for those in which the monaxons are excessively developed in size and number to form a furry protective covering. In my specimens from Roscoff, even from the same rock, I find some which, viewed with a lens, appear smooth, others which appear hispid; the difference between them is merely one of the length attained by the monaxons (compare figg. 10-13, text-fig. 94, p. 377). The same is true of L. complicata, and there can be no doubt that these sponges respond readily in this manner to differences in their surroundings. Of other species of Ascons in Haeckel's monograph, I feel no doubt whatever that his Ascortis corallorhiza is founded on a specimen of this species with rather large and thick spicules (compare figg. 15 «-15 f , text-fig. 95, p. 379). Here also we have a connexive variety, Ascandra corallorrhiza, mentioned. Systematists subsequent to Haeckel have for the most part recognized and identified this sponge correctly. A specimen, however, in the British Museum from Trieste, labelled L. variabilis, is certainly not this species. L. variabilis does not, to the best of my belief, occur in the Mediterranean ; but it is impossible, I repeat, to make definite statements about the distribution of Ascons in the present confused state of their nomenclature *. * Kirkpatrick, in 1901 (Brit. Mus. Rep. ‘ Southern Cross ' Collections, p. 317), identified an Antarctic sponge as L. variabilis ; but having been able, by the author's kindness, to examine the specimen I am in a position to state that it is not L. variabilis but a species, apparently new, allied to L. complicata. |