144 MEMBKANIPORID^. 



?Tata rugosa (part.), Van Ben. Bull. Ac. Eoy. Belg. xvi. no. 12, 648, pi. ii. 

 fig. 12. 



Oallopora lineata, Gray, B.M. Bad. 109. 



Eeptelectrina lineata, B'Orb. Pal. Fraii9. Terr. Oret. 334. 



Membranipora lineata, Busk, B.M. Cat. ii. 58, pi. Ixi. fig. 1 : Alder, North. 

 Cat., Trans. Tynes. Field Club, iii. 143, pi. viii. fig. 1 : Smiii, 

 forma 2, CEfvers. K. Vet.-Ak. Forh. 1867, 364 and 390, 

 pi. XX. fig. 23 ; Florid. Bryoz. pt. ii. 7, pi. ii. fig. 62 : Man- 

 zoni, Bryoz. foss. Ital. Ooutrib. iv. 10, pi. ii. fig. 13 \_not pi. iii. 

 fig. 14]. 



Zocecia oxsH, slightly expanded below, separate ; the mar- 

 gin with 6-12 spines, of which two are placed at the 

 top of the cell and directed somewhat upwards, the 

 second pair stand erect ; and the rest, which are slender, 

 and not flattened, bend inwards ; a rather large, raised 

 avicularium at the bottom of the cell, with triangular 

 mandible directed downwards. Ooecia large, globose, 

 shining, with an arched rib towards the top, an avicu- 

 larium usually on one side of it above, with the mandible 

 pointing upwards. 



Colonies forming subcircular patches. 



Range of Variation. The spines vary in number, but are 

 always less numerous than in the two following species, 

 twelve being about the maximum, and eight or ten the 

 more usual number. They are sometimes almost erect, 

 but more commonly they bend slight It/ inwards. 



A variety occurs (a) in which the margin is armed with 

 six spines only, two at the top and two on each side. The 

 cells are larger than usual, and the border rather broad 

 and crenate. The avicularia are very large and much 

 elevated. 



The cells also vary somewhat in shape and size. Nor- 

 mally they are pretty regularly oval, widening a little 

 Ijelow ; but occasionally they are much shortened and 

 almost orbicular in form. Sometimes they lie rather 

 widely apart. 



