180 MICUOPORII),E. 



aperture. This lid falls like a trap-door, and when down 

 covers a considerable portion of the front of the cell. In 

 the ovicelligerous cells the orifice is larger than in the 

 ordinary zooecia, and of different form. There is a close 

 resemblance between the ooecia of the present species and 

 those of S. Rozieri, Audouin. 



Genus SETOSELLA, Hincks. 



Der. A clira. formed from seiom, bristly. 



Membranipora (part.), Busk. 



CuPULARiA (part.), Smitt, Floridan Bryoz. ii. 14. 



Setosella, Hincks, Ann. & Mag. N. H. Sept. 1877. 



Generic Character. — Zoarium incrusting. Zo(ecia 

 witli raised margins; front depressed and wholly calcareous ; 

 aperture semicircular. Vibracular cells alternating with 

 the zoacia throughout the colony. Vibraculum slender 

 and setiform. 



In this genus each of the zooecia has a vibracular cell 

 immediately above it; the vibraculum is of the more 

 highly specialized type, and exhibits no trace of the fixed 

 beak-like structure which is found in connexion with the 

 more rudimentary transitional forms. The zooecia agree 

 in general character with those of Micropora. 



There is also a resemblance between Setosella and Cupu- 

 laria, Busk, in the mode in which the vibracular cells are 

 distributed over the colony ; and Smitt wovild unite the two 

 forms in one generic group. As I cannot subscribe to his 

 fundamental principle, that the plan on which the cells are 

 associated in the zoarium is of no account as a generic 



