62 



fractured surfaces of specimens as in microscopic sections ; 

 and tlie margins are apparently plain. 



The tabuljB on tlie other hand are perfectly complete, thin, 

 delicate, and about three in the space of one millimeter to 

 three in that of two millimeters, but irregularly placed as a 

 rule. The original form of the corallites was undou.btedly 

 polygonal, but from the deposition of sclerenchyma they have 

 become more or less cylindrical and oval, or irregular in section. 

 I have not seen any good examples of the surface, but so far 

 .as observed the mouths appear to be simply at right angles to 

 longer axes of the corallites, to be without opercula, and not 

 to have either lip raised above the other. 



A very marked difference exists in ranrose portions in the 

 width ot the axial and peripheral portions, the former largely 

 predominating, whilst the non-amalgamation of the walls in 

 the same region is usually very apparent. Septa seem to be 

 absolutely absent, whether as spines or tubercles. I have 

 adopted the character of the nural pores as the distinguishing- 

 feature of F. grandipora, notwithstanding the fact that in some 

 species of FavosUes the number of pores on each coral lite face 

 is variable. In the present instance, however, the arrangement 

 of the pores appears a constant feature throughout a suite of 

 fifty specimens, and it may therefore be justifiably used for 

 specific distinction in this case. In PI. viii., Fig. 7, is 

 represented the horizontal section of the axial region taken 

 from a polished specimen, and therein will be noticed the 

 broken-up condition of the primordial wall. It is, however, 

 nearly always visible at the angles of the cells, to the 

 exclusion of the sides, and then has a more or less stellate 

 appearance. In some thin sections prepared for the microscope, 

 on the other hand, now before me, this wall is tolerably 

 continuous and regular. The secondary dejjosit remains 

 very constant in its thickness, and does not appear to attain 

 the inordinate growth towards the final period of increase of 

 tlie corallites, so characteristic of the genus Pacltypora. 



Class GASTEROPODA. 



Qrder PliOSOBRANCIIIATA. ' 



Family Eulimid^'E. 



Genus Xiso, Risso, 1826. 



(Nist. Nat. Europe, Merid., iv., p. 218.) 



NiSO (VeTOTUBA) BRAZIERI, sp. 710V. 



(PI. viii.. Figs. 4 & 5 ; PL ix.. Figs. 2 & 3.) 



Sp. Char. — Shell turriculate, polygyrate, subulate, elongately 

 conical, and very slowly tapering, straight sided, and no more 

 than twelve whorls j the latter are liat, narrow, with closely 



