CORBITELLA AND HETEROTELLA. 19 



Heterolella corbicnla. Gray, '67, p. 531 ; PL xxvin, fig. 2. 



— Gray, '72, p. 457. 

 Habrodictyon corbicula. W. Thomson, '68, p. 129 ; PL iv, 



fig. 1. — Cartee, '73, pp. 361, 367. 

 Habrodictyon speciosum in part. Marshall, '76, p. 129. 

 Habrodictyum speciosum in part. Schulze, '86, p. 42. — 



Schulze, '87, p. 99. 

 Corbitella corbicula. Schulze, '00, p. 156. 



In the zoological museum of the Jardin des Plantes there 

 exist three specimens bearing the name " Alcyone ell 'um corbicula^ 

 All come from the Island of Bourbon. In my opinion they 

 represent a distinct species for which a distinct genus should be 

 allotted. 



Two of the specimens are evidently those that were remarked 

 upon by Bowerbank ('67, pp. 358, 359) ; all the three seem to 

 have been examined by W. Thomson ('68, pp. 129-131). For 

 the sake of reference I will call them Specimens A, B and C. 



Specimen A. This is the specimen which is labelled " Al- 

 cyoncellum corbicula Val. Tiré par 80 brasses de profondeur 

 dans la rade St. Denis de Bourbon par Mr. Leschenault, 1819." 

 Of all the three specimens it is the one that earliest became 

 known, in that Bowerbank, as early as 1858, had figured some 

 spicules from it and in 1867 had given a short account of it, 

 claiming its distinctness as a species from all other " Alcyoncellum " 

 known to him. 



The specimen is the torn upper end of a tubular Euplectellid 

 sponge, consisting of a partly damaged, roundish and flatly convex 

 sieve-plate, 50-58 mm. in diameter, and of the adjoining part of 



