OK THE SELENARIAD.fi, CONESCHAKELLINID.E, ETC. 401 



placed in a new genus. It is the Discoporellaoi d'Orbigny with C. umbellata 

 as the type, but the name having long been used, in mistake, for a 

 Oyclostomatous genus it is better dropped. 



These two structures having been briefly referred to, the Selenariadse can 

 be considered, and an attempt made to understand the relationship and 

 limitations of the group. In all the growth is from the apex, and in 

 Cupularia, Selenaria, and Luiiulites it is known that under the apex there is 

 often a grain of sand, a flake of shell or stone, or very frequently the shell 

 of a foram. This was, so far as T know, first pointed out by Defrance, but 

 has since then been frequently and almost amusingly rediscovered, being 

 alluded to by Michelin, Goldfuss, Reuss, Stoliczka, Busk, Beissel, 

 Gabb & Horn, Waters, Maplestone, Robertson, Canu, and Harmer, though 

 frequently it has been thought to be a characteristic of some one species or 

 genus (see PI. 29. figs. 1, 7, 8, 9, 10, and PI. 30. figs. 10, 12). 



The calcareous shell of the Selenaridan colony usually entirely encloses 

 the hard base on which the growth started, showing no sign of the support 

 either above or below, though sometimes the growth is on a much larger 

 stone, as in some specimens of Cupularia eanariensis from Petit Tahou, 

 Liberia (I'l. 30. fig. 12). It would seem impossible for a colony so heavily 

 weighted to float, nor can we think it could float in a reversed position. In 

 Vibracella trapesoidea, Reuss, there is in several specimens a small projection 

 on the under surface below the apex, caused by the presence of a very young 

 foram, but a few are found growing on much larger specimens of this 

 Orbitoides stellata, Giinib., or, as I am told it ought now- to be called, Ortlw- 

 phragma (see PI. 29. fig. 10). This Vibracella grows on the foram, and then 

 grows beyond it, like an inverted cup, though in the specimen figured 

 perhaps simultaneous growth of both organisms had taken place. When I 

 first described * Vibracella trapezoidea, Reuss, only small flat pieces were 

 available, but since then a number of disk-like forms, from Bocea di Sciesa, 

 Colle Berici, N. Italy, have been cleaned up, closely resembling in size and 

 shape Cupularia eanariensis. From the same locality I have a few specimens 

 of Mamillopora bidentata, Rss., also with the Orbitoides attached to the lower 

 surface, but not centrally, nor have the majority anything attached, so that 

 the few cases are probably accidental. No sand or other support has been 

 mentioned as occurring in Mamillopora, Batopora, or Conescharellina. 



Returning to Cupularia and Selenaria, the larva settles on the support 

 mentioned, and round the primary zooecia there are in Cupularia, and usually 

 in Selenaria, eight zooecia which are much smaller and shallower than the 

 peripheral zooecia, and often in these smaller zooecia there is no sign of 

 there ever having been an opercular opening. In Luiiulites there arc 



* '• North Italian Bryozoa," Quart. Journ. Geol. Soc. vol. xlvii. p. 11, pi. 1. tig-, i'3 (1891). 



