SCHIZOPORELLA A.LDERI. 243 



Localities. Shetland (A. M. N.) : St. Andrews, very 

 common (Dr. M'Intosli) : Wick and Peterhead, on stones 

 from deep water and between tide-marks (C. W. P.) : 

 Lamlash; Llandudno; Isle of Man; South Devon ; Ilfra- 

 combe (T. H.) : Hastings (Miss Jelly) : Dublin Bay 

 (Hassall). 



Geographical Distribution. Bahusia, on sea-weeds, 

 not common, 10-12 fathoms (Smitt) : Adriatic, rare, on 

 stones (Heller). 



SCHIZOPORELLA AlDERI, Busk. 

 Plate XXXVI. figs. 9, 9 a, 10. 



Alysidota AxDEiu, Busk, Quart. Journ. Micr. Sc. iv. (1856), 311, pL ix. 



figs. 6, 7 : Norman, Shetland Pol., Eep. B. A. 1868, 306. 

 Lepralia Barleei, Busk, Quart. Journ. Micr. Sc. vii. (1860), 143, pi. xxvi. 



figs. 1, 2. 

 MoLLiA VULGARIS, forma ANSATA, Hippothooid var., Sniitf, I. c, Krit. Fort. 



iv. 15 & 104, pi. xxF. fig. 81, (?)79. 



Zocecia broad-ovate, distinct, subgranular, sometimes 

 punctured, glossy, irregularly massed together, or dis- 

 posed in a single branching series; orifice arched above, 

 inferior margin straight, with a central notch ; imme- 

 diately below the mouth an umbo ; occasionally a small 

 avicularium with acute mandible, pointing obliquely 

 downwards, on one side a little below the mouth, rarely 

 on both sides. Ooscia globose, prominent, smooth, 

 usually with a central umbo. 



Range of Variation. This species assumes two very dis- 

 tinct modes of growth. The cells are either massed to- 

 gether, so as to form a continuous crust, or they run out 

 into chain-like linear series, which send off branches in a 

 dendritic fashion. 



There is a striking contrast in habit between the two 



R 2 



