SCRUPOCELLAKIA. 43 



seems not to exceed three, except in the case of the ter- 

 minal cell at the bifurcation of the branches, which bears 

 an additional one in the centre of the upper margin. Two 

 are generally present on the outer side of the cell at the 

 top ; and immediately beneath these is placed the very 

 small lateral avicularium. A single spine is also deve- 

 loped, I believe, close to the pedicle of the operculum. 

 The operculum originates very high up on the margin of 

 the cell, and tends somewhat obliquely downwards ; the 

 lamina expands almost exclusively below, and fills in the 

 inferior portion of the aperture. The surface of the 

 zoarium is smooth and shining. 



Menipea Smittii, Norman ( = Cellularia ternata, forma 

 duplex, Smitt), a Spitzbergen species, is nearly allied to 

 the present form, but differs from it in not being furnished 

 with either operculum or spines. 



Genus SCRUPOCELLARIA, Van Beneden. 



Der. From gcntpus, a stone, and cclla, a cell. 



SCRCPOCELLARIA, Van Beneden, "Recherches" &c. 1844. 



BICELLARIA, sp., Blainvillo. 



CELLULAKI A, sp., Pallas : Johnston: Smitt. 



CELLARIA, sp., Ell. &, Sol. : Laink. 



SCRUPARIA, sp., Oken. 



CAKDA, ep., Busk. 



GENERIC CHARACTER. ZOARIUM jointed. ZO<ECIA nume- 

 rous in each internode, rhomboid ; aperture with or u-ittioiit 

 an operculum ; a sessile avicularhnu jilaced laterally at the 

 n}>l r and outer angle, and a vibraculum in a bend or sinus 

 on the loirer part of the dorsal surface ; frequently an 

 avicularium on the front of the cell. 



SUM i. of the differences between this and the preceding 

 genus have already been pointed out. The leading cha- 



