180 MICHO?ORII>;E. 



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

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

 the ovicelligcrous cells the orifice is larger than in the 

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

 resemblance between the ooccia of the present species and 

 those of S. Rozieri, Audouin. 



Genus SETOSELLA, Hincks. 



Der. A dim. formed from setosa, bristly. 



MEMHRANIPORA (part.), Busk. 



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



SETOSELL.V, HinckB, Ann. & Mng. N. H. Sept. 1877. 



GENERIC CHARACTER. ZOARIUM incrusting. ZOCECIA 

 with raised margins ; front depressed and wholly calcareous; 

 aperture semicircular. VIBRACULAR CELLS alternating with 

 the zocecia throughout the colony. VIBRACULUM slender 

 and setiform. 



IN this genus each of the zocecia 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 zooscia 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 arc 

 distributed over the colony ; and Smitt would unite the two 

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

 fundamental principle, that the plan on which the cells :uv 

 associated in the zoarium is of no account as a generic 



