LEPRALIA EDAX. 311 



a feature. The central mucro and the marginal punc- 

 tures, which are pretty constant characters of L. hippopus, 

 are absent in the kindred species. I may add that the 

 two differ remarkably in general appearance, and that 

 the one is (so far as we know) a northern and the other a 

 southern form. 



The only British example of L. hippopus which I have 

 heard of, is from the Northumberland coast, and agrees 

 in all respects with specimens from the Gulf of St. Law- 

 rence, which I owe to the kindness of Principal Dawson 

 of M'Gill University. 



Lepralia EDAX, Busk. 

 Plate XXIV. figs. 7, 7 a. 



Cellepoka EDAX, Busk, Crag Pol. 59, pi. ix. fig. 6, pi. xxii. fig. 3; Quart. 



Journ. Micr. Sc. n. ser. i. 154, Zoophytol. pi. xxxiv. figs. 3, 



3a: HincJcs, Devon Cat., Ann. N. H. ser. 3, ix. 304 (48 



Sep.). 

 Lepralia edax, forma tvpica and forma calcarea, Smitt, Flor. Bryozoa, 



pt. ii. 63, pi. xi. figs. 220-223. 



Zoarimn rather massive, usually moulded on a small uni- 

 valve shell, occasionally forming erect, pumicose stems. 

 Zooecia ovate rhomboid or hexagonal, very irregularly 

 disposed, surrounded by a marginal line, and punctured 

 round the edge ; the cell- wall rising more or less 

 towards a prominent umbo, placed below the mouth, 

 which is often prolonged into a tall mucronate process; 

 surface roughened, often striated by radiating furrows ; 

 orifice rounded and expanded above, contracted a little 

 below the middle, where there is a small denticle on 

 each side, lower margin slightly curved outwards ; 

 peristome not elevated, unarmed ; small oval avicularia 

 irregularly distributed, often wanting ; large avicularia, 

 with a pointed mandible, placed on a distinct area 



