OF MADEIRA AND NEIGHBOURING ISLANDS. 289 



radiating ribs coalesce with each other by crossbars, so as to form roundish 

 openings or " lateral lacunes," * as I have termed them. In fact this Madeiran 

 I'orm in its structure is in all respects a true Cribrilina. 



Membraniporella sceletos (Busk). B., H., W. (PI. 36. fig. 8.) 



1858. Membranipora sceletos, Busk, Quart. Journ. Micr. Sci. vol. vi. p. 262, pi. 60. 



fig. 3. 

 1880. Memhranipora sceletos, liincks, Ann. Sc Mag'. Nat. Plist. ser. 5, vol. vi. p. 73. 

 1898. MeinbraniiJora sceletos, Waters, '' On Membraniporidae," Liun. Soc. Journ., Zool. 



vol. xxvi. p. 677, pi. 49. figs. 2-6. 

 1903. Memhraniporella neptuni, J. Calvet, Result. Camp. sci. Prince de Monaco, xxiii. 



Brjozoaires, p. 38, pi. 5. fig. 2. 



The form of the spines arching over the zooecium in this species, instead of 

 being horizontally compressed and widened as is the case in M. niticla, are 

 verticall_y, that is laterally, compressed ; so that, to use Mr. Waters^s words, 

 " under the microscope we are looking down upon the narrow edge of the 

 flattened spines." These spines usually remain isolated from each other ; 

 even although they may cross in the centre. But this is not always the 

 case. In several examples which have come under my observation, they 

 are coalesced (see right-hand zooecium in figure here given), though in 

 consequence of the ribs meeting each other at different angles, they may still 

 be separately distinguished, the union not being so absolute as in M. nilida. 

 Yet it would seem that we must regard M. sceletos as a member of the o-enus 

 to which I here remove it. 



CupuLARiA guineensis, Biish. B. (PL 37. figs. 2-().) 



1854. Cupularia (juineensis, Busk, Cat. Marine Poljzoa, p. 98, pi. 114. 



1859. Cupularia canarimsis, Busk, Quart. Journ. Micr. Sci. vol. vii. p. 66, pi. 23. 



figs. 6-9. 

 1859. Ciqndaria canariensis, Busk, Crag Poljzoa, p. 87, pi. 13. fig. 2. 

 1873. Membranipora canarierisis, Smitt, Floridan Br3^ozoa, p. 10, pi. 2. figs. 69-71. 

 1884. Cupularia (juineensis, Busk, ' Cliallenger ' Polyzoa, p. 206, pi. 14. fig. 6. 



Waters unites also with this species C. stellata, Busk (Brit. Mus. Cat.) 

 and C. monotrema, Busk ('Challenger"). 



Zoarium only slightly raised, saucer-shaped ; zooecia narrowly lozenge- 

 shaped, calcareous margin simple, without any inward projecting develop- 

 ments. Lower side divided into more or less regular quadrate portions, each 

 of which would seem to represent a zocecium ; these divisions contain pores, 

 usually four in number, but occasionally only two or three. The divisions, 

 though normally four-sided, are occasionally five or six-sided, more especially 

 towards the centre, as figured by Busk in C. guineensis (Cat. Polyzoa). 



Common in 50-70 fjithoms. 



* Vide Norman on the structure of CiibrilinidtB in " Notes on tlie Natural History of 

 East Finmark," Ann. & Mag. Nat. Hist. ser. 7, vol. xii. 1903, pp. 90-99. 



