6 ART. 9. — I. 1JIMA ! HEXACTINELLIDA. 



tellids in the Paris museum, I had to conclude that one of the 

 spicules mentioned and the single one figured by him (/. c, fig. 

 2 a) — a spicule which chiefly weighed with him in regarding this 

 species as a distinct one — does not belong to the species at all ! 

 I recognize in that spicule the small spiny hexactin (vide PL, 

 figs. 20-23) which is characteristic to, and not uncommonly 

 found in, Helerotella corbicula and which is easily distinguishable 

 from a similar spicule of Corbitella speciosa. The said spicule was 

 held by W. Thomson as probably identical with Bowerbank's 

 " bifurcate rectangulated hexradiate spicule " (Boweeb. '58, PI. 

 XXV, fig. 38; also '64, PL VIII, fig. 188). I think W. 

 Thomson was quite correct in this identification ; for, Bower- 

 bank's above named spicule was taken, not from G. speciosa, but 

 from " Alcyoncellum corbicula " obtained in 80 fathoms off the 

 Island of Bourbon (vide Bowerb., '67, p. 358). As before 

 mentioned, W. Thomson by an unfortunate confounding of labels 

 ascribed to the only specimen of C. speciosa the labelling " Al- 

 cyoncellum corbicula Val. Tiré par 80 brasses de profondeur 

 dans la rade de St. Denis de Bourbon " etc, Probably this 

 labelling and the spicule in question belonged together, but 

 neither of them to the C. speciosa. This tends also to explain 

 that W. Thomson has entirely overlooked the spiny microxy- 

 hexactin and the discohexasters soon to be described from C. 

 speciosa. 



To return to my own observations on the loose tissue 

 spiculation, the parenchymalia (accessoria) consist mainly of the 

 well-known, long, slender diactins, with which are associated a 

 not inconsiderable quantity of hexactins. The diactins may be 

 as thick as 20/', but the majority are much thinner and of a 

 filamentous appearance (down to 7 / J - in thickness near the center). 



