324 Z. ASCIDIOIDA. Plumatella. 



Trembley, and his Tiibnlaria gelatinosa, in a living state, and he as- 

 serts that the latter — a Plumatella— differs from the former — an Al- 

 cyonella — not solely in habit,* but in having fewer, shorter, and more 

 recurved tentacula. " Interaneis quoque" he adds, " a prsecedenti 

 differt et distinctissima est hcec species, quae interdum in iisilem cum 

 praecedenti (semper rariore, adeoque, ut videtur, minus prolifica) re- 

 peritur aquis." Muller's description of Plumatella repens certainly 

 affords nothing in opposition to Raspail's theory, but on the contrary 

 may be deemed favourable to it, since he tells us that it is intermedi- 

 ate between the very species which Pallas considered so widely diffe- 

 rent, possessing many of the characters of both, and differing princi- 

 pally in the appearance of the polypidom. Lamarck* perceived the 

 affinity of the genera, which he nevertheless kept separate, resting 

 the distinction on the massive and ramous forms of the polypidoms. 

 Baer, apparently speaking from personal examination of the produc- 

 tions in question, has expressed his conviction of the perfect distinctness 

 of Alcyonella and Plumatella, and this subsequent to his knowledge of 

 Raspail's Memoir : and Milne-Edwards has still more recently shown 

 that this essay had at least not conveyed perfect conviction to his 

 mind, otherwise he would scarce have expressed himself in this man- 

 ner : " II nous parait en effet probable que ces Polypes, observes a 

 des periodes diverses de leur developpement, ont ete pris pour des 

 animaux differens et decrits sous des noms particuliers. Mais il se- 

 rait possible aussi que les formes transitoires de I'Alcyonelle decrites 

 par M. Raspail se rencontrassent d'une maniere permanente chez 

 d'autres Polypes, et par consequent, on ne pent encore rayer des ca- 

 talogues zoologiques la longe suite d'especes mentionnees ci-dessus." 

 Lam. Anim. s. Vert. 2de edit. ii. 116. — Under these circumstances I 

 have deemed it the best course to keep the genera separate, as least 

 likely to perplex the student. 



Of the P. Sultana little is known. 1 have seen a living specimen 

 in the possession of Sir John G. Dalyell, but had no opportunity of 

 making an examination of it. Naturalists wait with some impatience 

 the publication of a work from this ingenious observer, on which, it 

 is understood, he has been long engaged, and which will disappoint ex- 

 pectation if it does not disclose many novel facts, and illustrate many 

 present obscurities, and give additional respect and permanence to 

 his name and reputation as a naturalist. 



• " Habit is a general agreement in growth and appearance." f.imifeus. 



