No. 2.] NICHOLSON — NEW FOSSILS. 139' 



small, apparently forty-eight in number. Epitheca thin, with a 

 few shallow undulations of growth, but destitute of vertical 

 stria) or costae. 



This species is closely allied to Z. gigantea, Lesueur, but ap- 

 pears to be clearly distinct; though the above description is 

 founded upon but a single specimen, which is .ill that I have as 

 yet obtained. It differs from Z. gigantea in the greater pro- 

 portionate thickness, and much smaller number of the septa^ 

 and in the greater remoteness of the tabulae. Thus in Z. gigan- 

 tea the septa are from seventy to one hundred and forty in num- 

 ber, and they are alternately small and large; whilst their thick- 

 ness is not particularly great, and the distance between the 

 tabulae is not excessive. Z. fenestra ta is also a smaller form 

 than Z. gigantea. From Z. j^^'oUfca, Billings, the present 

 species is distinguished by its greater size and more cylindrical 

 form, and the much smaller number of the septa, as well as by 

 the fact that the septa are not alternately of different sizes. 

 Zaphrentis patula of Edwards and Haime, possesses forty equal 

 septa, but is of a much smaller size, and its shape is much more 

 turbinate. Z. centralis, of the same authors, is also very much 

 more diminutive in its dimensions. 



The tabulae of the circumference of the coral in Z. fenestrataj.^ 

 where they bend downwards to meet the epitheca, appear to be 

 clearly of the nature of highly developed dissepiments ; since 

 they are not placed at exactly the same level in contiguous inter- 

 septal loculi. The specific name is in allusion to the peculiar.- 

 fenestrated appearance exhibited by portions of the coral from., 

 which the epitheca has been removed, when the interseptal loculi 

 are seen to be crossed at intervals of from two to three lines by 

 the obliquely descending tabulae, producing the appearance of a 

 series of oblong fenestrules. 



Length of the only specimen observed five inches (real length, 

 probably nearly twice as much) ; diameter of summit one incb- 

 and a half. Calice and fosette unknown. 



Locality and formation. — Corniferous limestone^ Port Col- - 

 borne. 



Genus Blothrophyllum (Billings). 



'' Corallum simple, turbinate or cylindrical. Internal struc- - 

 ture consisting of a central area occupied by flat transverse dia- 

 phragms, an intermediate area with strong radiating septa, anc^^. 



