264 ME. ARTHUE W. WATERS ON 



Zocecia only sligLitly raised, smooth, without any large avicularia, 

 but with a small one (with a semicircular mandible) in the aper- 

 ture, and small round ones over the surface. The oral aperture 

 is straight on the proximal end and becomes much wider towards 

 this edge. There is a denticle on each lateral wall of the oral 

 aperture. The dorsal surface is slightly granular and has few 

 vibices, and these usually cross the branch near the end of the 

 fenestrse. The ovicells as a rule are not much raised, in fact are 

 often only recognized by the cleft. 



This seems to be common near Naples and Capri, and I have it 

 fossil from the Pliocene of Bruccoli (Sicily) and Testa del Prado 

 (Calabria). In the shape of the operculum, in having an avicu- 

 larium within the aperture, and in structure of the dorsal surface 

 it approaches closely to R. JBeaniana, though even in these cha- 

 racters there is a slight difference between the two. Further the 

 zoarium is much stouter than in the northern Beaniana, and the 

 avicularium is placed diagonally within the aperture, nor is there 

 any rostrum or avicularium, and of course the denticles projecting 

 Irom the rostrum or avicularium of B. Beaniana are wanting. 



In B. atlantica, B., from station 75 of the ' Challenger,' some 

 zocecia have a small round avicularium on the lip of the aperture, 

 while others have a rather large triangular one, showing that too 

 much importance must not be attached to the shape of the avicu- 

 larium. I do not think this is the B. cellulosa of Yan Beneden, 

 which has a large erect avicularium. 



Eetepoea Soi/Anderia, Bisso. (PI. VI. figs. 1-4.) 



Eetepora Solanderia, Risso, Hist. Nat. de V Europe Merid. vol. v. p. 344. 



Retepora arborea, Jullien (noa Risso), Bryozoaires Dragagesdu Travail- 

 leur, Bull. Soc. Zool. de France, vol. vii. p. 21, pi. xvi. figs. 49, 60. 



Zoarium branched in one plane, not usually reticulated, branches 

 thick. The zocecia on each side of the median line have a large 

 avicularium on a raised rounded avicularian chamber, with the 

 mandibles directed inwards. The outer zocecia have no avicu- 

 laria, the terminal zocecia have spines. Labial pore distinct, 

 with a slight fissure. Ovicells cucuUate, with a wide opening. 

 The dorsal surface has regular vibices, and in each area there is 

 a large raised avicularium somewhat similar to those upon the 

 front, usually directed outwards, but also occurring in various 

 positions. On the dorsal surface there is frequently at the 

 junction of two branches a large avicularium with triangular 

 mandibles. This is the equivalent of the fenestral avicularia 



