286 T. A. STEPHENSON 



at any rate tendencies in this direction in other species 

 (cf. P. sphaerulata), and I leave it at that for the time 

 being. I think my fusion of B u n o d o s o m a with R i v e t i a 

 and Phymactis can be supported in the same sort of 

 way as Torrey's fusion of Bunodactis with Antho- 

 pleura, &c. It has been seen from time to time that 

 sphincter-detail alone cannot always separate species ; that 

 acrorhagi are too variable (cf. P. granulifera in which 

 they may be well developed or barely discernible) to be invari- 

 able ground for separation ; and there do not in this case seem 

 to be any valid distinctions to be based on the vesicles. The 

 siphouoglyphe- variation and lack of directives in P . (B i v e t i a) 

 papillosa has parallels elsewhere, and is hardly in itself of 

 generic weight. 



Cystiactis, M. Edw., 1857. (See Haddon and Duerden, 1S9G, 

 p. 154.) 

 Phlyctenactis, Stuckey, 1909, p. 396. 



Phyllactidae with the coluiim covered by simple sessile or .slightly 

 pedunculate vesicles. No acrorhagi. lyongitudinal inusculature of 

 tentacles mesogloeal. Sphincter absent or diffuse. l*iiuiary mesen- 

 teries may be sterile. Retractors chfluse. 



Species : 



C. tuberculosa, Q. and C, 18.3.3. p. 159. (8ee Haddon «nd 

 Duerden, 1896, p. 156 ; Lager, 1911.) 



C. retifera, Stuckey, 1909, p. 396. 



C. morrisoni. Stuckey, 1909, p. 396. 



?C. Koellikeri, Pax,' 1910, p. 180. 

 And other older species not yet well known. 



I have placed Stuckey 's Phlyctenactis under Cysti- 

 actis, with which it seems to be identical, especially if the 

 tentacular muscle is mesogloeal, as his figures lead' one to 

 believe. C. Koellikeri may belong here or under Phy- 

 mactis. Cystiactis is distinguished from Phymactis 

 by its simple vesicles, constant absence of acrorhagi, meso- 

 gloeal tentacle-muscle, and on the whole weaker musculature. 



BuNODEOPSis, Andres, 1880. (See Duerden, 1897 and 1902.) 

 Phyllactidae with the body broad and flattieh below, covered with 



