PROF. OWEN ON EUPLECTELLA. 205 



The component filaments of the parietal fibres are chiefly of two kinds ; the one' sim- 

 ple, cylindrical and smooth, the others' barbed at pretty regular distances through their 

 whole extent, like the hair of certain caterpillars : I have also observed a few long fila- 

 ments, which were simple at one extremity and barbed at the other'. These compo- 

 nent filaments consist of a material like the dried gluten of marine plants, containing 

 a small proportion of azote, and burning away to a charry silicious residuum. 



If the basal aperture of the cone were open, the resemblance to some of the known 

 reticulate Alcyonoid sponges would be very close, especially to that called Alcyonellum 

 gelatinosum by M. De Blainville* (Alcyonellum speciosum, Quoy et Gaimard') : its closure 

 by the reticulate convex frilled cap, in the present instance, establishes the generic 

 distinction ; and in the exquisite beauty and regularity of the texture of the walls of 

 the cone, the species surpasses any of the allied productions that I have as yet seen or 

 found described. I propose, therefore, to name it Euplectella Aspergillum. 



Since the foregoing description of the Euplectella was penned, that unique specimen 

 has been purchased by my friend WiUiam John Broderip, Esq., whose cabinet it now 

 graces. It has been entrusted, with his wonted liberality, to Mr. George B. Sowerby, 

 Jan., during the long period which has been devoted to the engraving of so deUcate and 

 complicated a subject, and I cannot conclude without expressing my obligations for the 

 facilities thus afforded to the accomplished artist, and for his zealous and successful 

 endeavours to achieve a faithful representation of the Euplectella. 



PLATE XIII. 

 Fig. I. Side view, natural size. 



2. Basal extremity. 



3. Apical extremity. 



4. Single interspace or open cell and surrounding finer mesh-work, magnified. 



5. Component filaments magnified 150 diameters: a, Smooth filament; 



c, Toothed filament. 



• PI. XIII. fig. 5, a. « lb. fig. 5, c. 



' lb. fig. 5, b. 1 Manuel d'Actinologie, 8vo. 1834, p. 529. 



' Zoologie de 1' Astrolabe, 8vo. 1833, p. 302 ; Planches, Fol. Zoophytes, pi. 26. fig. 3. If the recognition of 

 the generic or specific identity of the specimen here figured be impracticable, by reason of its mutilated con- 

 dition, the generic name applied to it cannot be adopted while the Lamarckian genus of freshwater polypes, 

 Alcyoaella, is retained in zoology. 



VOL. III. PART II. 2 E 



