128 Prof. W. Thomson 07i the " Vitreous''^ S^wnges. 



3. Professor Owen recognizes, apparently from tlie figure in 

 the ' Voyage de 1' Astrolabe/ the generic distinctness of Habro- 

 dictyon from Eu2)lecteUa. He gets into confusion, however, 

 about the synonymy. '' If the basal aperture of the cone were 

 open, the resemblance to some of the known reticulate Alcyo- 

 noid Sponges would be very close, especially to that called 

 Alcyonellum gelatinosum by M. de Blainville [Alcyonellum 

 sj)eciosum, Quoy & Gaimard) ; its closure by the reticulate, 

 convex frilled cap in the present instance establishes the ge- 

 neric distinction." 



4. Dr. Bowerbank's references and remarks are curiously 

 inaccurate : Dr. Gray has, however, already done them full 

 justice at the close of a short paper in the ^ Annals ' for 1866, 

 except in one point. Dr. Bowerbank's definition of the genus 

 Alcyoncellum is utterly inapplicable to the Sponge which he 

 adopts as a type! and, in the simple process of adopting it as 

 such, he contrives either to misname the Sponge or to mis- 

 quote the authority. 



5. Dr. Gray does not succeed in throwing much light upon 

 the question ; for, still under the fatal spell, he notices Euplec- 

 tella aspergillum under the name of E. sjieciosa^ and says : — 

 " This Sponge was first described and figured, in 1833, by 

 MM. Quoy and Gaimard, in the ^ Voyage of the Astrolabe,' 

 p. 302, Zoophytes, t. 26. f. 3, under the name of Alcyoncellum 

 speciosum^ from a very imperfect specimen which had lost the 

 netted lid, the fringes on the outside, and a considerable por- 

 tion of the smaller, lower end of the tubes." * * * " There can 

 be no doubt of the imperfect state of this Sponge, from a com- 

 parison with a worn and crushed specimen in the British 

 Museum, that was obtained by Capt. Sir Edward Belcher, and 

 purchased at the sale of his shells." 



6 & 7. Dr. Gray has at length fully recognized EuplecteXla 

 and the species in the French Museum as belonging to distinct 

 genera ; nay, he has founded two new genera upon the speci- 

 mens in the Jardin des Plantes. I certainly suggested to Dr. 

 Gray, in May last, in a letter which he has quoted [p]). cit.)^ 

 to define a new genus for the French forms ; but I cannot 

 possibly consent to the splitting of that genus. Genera are 

 doubtless of the highest convenience if they represent grov2)s 

 of nearly allied species ; but to give a generic name to almost 

 every species, entirely does away with the value of the genera, 

 and, instead of assisting the student, only adds to his per- 

 plexity. For a time I doubted whether these two forms 

 were distinct species ; and I was inclined to regard the speci- 

 men of A. sj^eciosum as a variety grown imder peculiar cir- 

 cumstances, and the short A. corhicula Avith the netted lid as 



