156 MEMBRANIPORIDJE. 



MEMBRANIPORA DUMERILII, Audouin. 

 Plate XX. fig. 3. 



FLUSTRA DUMERILII, Aud. Expl. Savigny figypte, Polypes, pi. x. fig. 12. 

 MEMBRANIPORA MEMBRANACEA (part.), Johnst. B. Z. ed. 2, 328, pi. Ivi. fig. 7. 

 MEMBRANIPORA FI.EMINGII, Busk, RM. Cat. pi. cir. fig. 2. 

 MEMBRANIPORA POUILLETIF, Alder, North. Cat., Trans. Tynes. F. C. iii. 146, 



pi. Tiii. fig. 5; Quart. Journ. Micr. Sc. v. 248: Bitsk, Crag 



Pol. 32, pi. iii. figs. 4 & 6. 

 MEMBRANIPORA PUMERILII, Norman, Rep. Brit. Assoc. for 1866, 305: M'ln- 



tosh, Mar. Invert, of St. Andrews, 45. 

 MEMBRANIPORA LINEATA, 5, forma CNICORNIS, , stadium juvenile, Smitt, 



CEfvers. K. Vet.-Ak. Forh. 1867, 365 & 397, pi. M. fig. 29. 



Zooecia small, ovate, broad below, very regularly quincun- 

 cial ; margin granulated, with a thin edge ; spines four 

 (rarely six), placed two on each side, near the top of the 

 cell, the lower pair showing below the ovicell, one of them 

 sometimes enormously developed. Ooecia large, globose, 

 or elongated, strongly frosted ; a small pointed avicu- 

 larium on each side above, or on one side only ; man- 

 dible directed upwards and slightly outwards. In the 

 absence of the ovicell, an avicularium usually at the 

 base of the cell, placed transversely, with the mandible 

 directed downwards. 



Colonies forming a neat, pearly lacework. 



RANGE OF VARIATION. There are slight diversities in the 

 shape of the cell ; but in its prevalent and characteristic 

 state it is contracted at the top and broad below. The 

 ovicell is often much produced ; but it also assumes a more 

 rounded form. 



HABITAT. Chiefly on shells, stones, &c., from shallow to 

 deep water ; occasionally on Laminaria. 



LOCALITIES. Shetland, occasionally on Cellepora cervi- 

 rornis and shells; Hebrides (A. M. N.) : St. Andrews, 

 on bivalves from deep M-ater (Dr. M'Intosh) : Northum- 

 berland and Durham, on shells and zoophytes, especially on 



