SETOSELLA VUI.N EKATA. 181 



character, I am unable to assent to this view. The remark - 

 al)U- structure of the zourium in Cupularia, and its free 

 condition when adult, are points of much systematic value ; 

 and to these must be added the great development of the 

 vibrucula, and their (probable) assumption of a locomotive 

 function*. 



SETOSELLA VULNERATA, Busk. 



Plate XXI. fig. 7. 



MEJJBKAJUTORA VULKERATA, Busk, Quart. Journ. Micr. Sc. viii. (1800), 124, 

 pi. xxv. fig. 3 : Norman, Shell. Dredging Rep., Brit Aasoc. 

 Rep. 18*57, 303. 



SETOSELLA VULNERATA, Hincks, Ann. & Mag. N. H. for Dec. 1877. 



Zocecia somewhat pyriform or oval ; margin slightly raised, 

 smooth, unarmed ; orifice small, arched above, the lower 

 lip a little curved outwards ; lamina minutely granular, 

 rising rather abruptly towards the mouth, usually with 

 a narrow, slit-like fissure, slightly curved, on each side, 

 a little below the orifice. Long and slender vibraeula 

 distributed over the colony on distinct intercellular 

 areas, one immediately above each cell. Ooecia? 



Colonies forming very small, white, subcircular patches. 



OF VARIATION. There are sometimes considerable 

 differences in the size of the cells within the limits of the 

 same colony. The shape varies from suboval to pyriform ; 

 the cells are generally much narrowed towards the orifice, 

 and expand to a moderate degree below. The lateral 

 fissures in the lamina arc occasionally wanting. 



* Mr. Busk informs me (I'M lift.} that liis oonji-otuiv respecting tlic looo- 

 ni''ti\.- function of tlic vibrarul.-i amun^-i (lie funiiU !' .N. It nurimla (to 

 which Citj'ittin HI Ix-l'-TiiM has been continued hy actiiiil l?cr\ati"ii. 



