MICROPORELLA CILIATA. 209 



and 47° 35', and in W. long. 7° 6', from 89-205 fms. 

 (Sir James Anderson) : France, S.W. (Fischer) : California 

 (Miss Jelly) * : &c. 



Range in Time. English Coralline Crag, on sliell (S. 

 Wood) : Middle Pliocene beds (A. Bell) : Vienna basin 

 (Reuss) : Italian Pliocene beds (Manzoni) : Sicilian Plio- 

 cene, Bruccoli (A. W. Waters) : &c. 



This protean species presents itself in many disguises, 

 but is easily recognized amidst them all. Perhaps the 

 characteristic features are most completely veiled in the 

 variety with the hooded ovicell, in which the form of the 

 mouth is not apparent, and the pore is sometimes concealed 

 behind the wall which incloses the aperture in front; but 

 even in this case the lateral avicularium is a good dia- 

 gnostic. The wall is often incomj)lete towards the centre 

 (in some colonies it is always so), and a subcircular 

 opening is left, through which the pore may be detected. 



Busk^s Lepralia personata, from the Falkland Islands, 

 is evidently only a form of M. ciliata, the equivalent of 

 our hooded variety, although it has the pore outside in- 

 stead of within the wall -like extension of the ovicell. 



The diversities in size are very striking. On the same 

 shell, specimens may be met with in which the cells are 

 on a totally different scale, ranging from extreme minute- 

 ness to the full normal dimensions. 



In a variety, which occurs in Australia as well as in 



* In the Californian specimen, which I have seen, all the structural 

 features are yery pronounced. The wall of the cell is much calcified and 

 thickly punctured ; the pore is of unusual size, and the beautiful sieve-like 

 structure very apparent. The ooecium is large and with a prominent umbo 

 in front ; while the avicularia, which are much elevated, are developed in a 

 great proportion of the cells on both sides. This may be the Lepralia 

 Californica of Busk ; but if so, it seems to me that this species must rank 

 as a variety of the present form. In one or two instances I have met with 

 two avicularia on a British specimen. 



