660 MR. A. "W. WAIEES ON MEMBEANIPOEIDiE. 



Or three, as in JK. cratimila, piira, sceletos, ferfragilis (?) . 



Oy four, as in M. cylindracea. 

 " Or six or more, as in 31. liians, tuligera, Savartii, catenularia^ 

 tehuelcTia. 



On the lateral wall tliere may be two rosette-plates, as in 

 C. cristata ^ar. hilaminata, capensis, M. tri^unctata, catenularia,- 

 nitens, patellaria, radicifera, tenuirostris, soUdula, papulifera, 

 valdemunita, migulosa, perfragilis. 



Or four, as in M. pUosa, danica, pura, tehuelclia, maderensisy 

 corhula, pyrula, inarmata, craticiila, unicornis, lineata, aurita, 

 Dumerilii, SopMcd, acuta, patellaria var. imdtijuncta, Fle^ningii, 

 minax, trifolium, argentea, umhonata, granulifera, imhellis, 

 crassimarginata, Savartii, falcifera. 



Or six, as in M. Mans, permunita, fiustroides, bidens. 



Or numerous, as in M. tuligera, serrata, armata, sceletos, 

 punctigera, curvirostris, gregaria, imhricata. 



The combs in M. nitens, H., and M. tehuelclia, d'Orb., which, 

 almost divide the zocecia into two parts, are most interesting 

 structures, and the question is raised as to whether they must 

 be compared with the denticular plate in such species as 

 M. hians. 

 ■ The Memhranipora serrata is removed to JFlustra, and M. r6bo~ 

 rata is also removed from Memhranipora to JFlahellaris, for from 

 the shape of the zocecia and the position of the rosette-plates it 

 is clear that it belongs to the group of Menipea flahellum, L., 

 M. cirrata, Lamx., &c. (see my " jN"otes on Bryozoa from^ 

 Eapallo," Journ. Linn. Soc, Zool. vol. sxvi. p. 2). 



The groups proposed are : — 



No. 1. Chapeeta group. — The operculum is "complete" 

 (corresponding with the aperture), with, a low ridge on each side, 

 for the attachment of tbe powerful muscles. The rosette-plates 

 are mostly large, and about halfway between the front and 

 basal walls. Tbe ovicells have a separate operculum. Confined 

 to the Southern hemisphere. 



No. 2. Pteipoea group. — Ovicells unknown in recent forms, 

 but known in fossils. No avicularia. 



No. 3. M. piLOSA group {Electra, auct.). — No avicularia or 

 ovicells. Operculum with thickened border. Larva cyphonautes. 

 As far as examined the tertacular organs exist. 



