84 On two new Genera and Species of PoJyzoa. 



the Fenestelliclaj. The most anomalous point is the position 

 of the cells, or rather their mode of opening on the surface. 

 The cells open towards the interior of the funnel-shaped frond, 

 as in Retejyora, and in the upper portion thej seem to open 

 simply at the bottom of the deep intercarinal grooves, into 

 which the fenestrules also open ; so that there is here no 

 special difficulty, if, as seems tolerably certain, the keels are 

 not here connected by an imperforate membrane, and the 

 grooves thus remain open to the access of sea-water. Near 

 the base, however, the keels are clearly connected by a con- 

 tinuous imperforate membrane, and the deep intervening 

 grooves are filled up by a vesicular calcareous tissue, so that 

 the sea-water could not have gained access to the mouths of 

 the cells. The only explanation that I can offer is that the 

 basal portion of the polyzoaiy may perhaps have been gra- 

 dually overgrown internally by this layer of vesicular tissue, 

 and may thus have been practically killed, whilst the upper 

 portion remained open to the sea and genuinely alive. If this 

 was not the case, I cannot explain the undoubted facts. 



The enormous internal keels, whether free or connected 

 together by membrane, give an extraordinary depth and 

 thickness to the polyzoary ; and the fenestrules do not extend 

 to more than about one fourth of this depth from the outside ; 

 nor do the cells. In Hemitryjxi^ Phill., the fenestrules do 

 not extend through the entire thickness of the polyzoary ; but 

 in this genus the fenestrules are confined to the inner surface 

 of the funnel-shaped frond, and the cells open externally. In 

 Cryptoj'ioraj Nich., again, the outer and inner surfaces of the 

 polyzoary are both imperforate, and the cells open into a 

 central space, which is crossed by regularly placed pillars 

 having a direction perpendicular to the plane of the frond. 



The following is the only species of the genus Carinopora 

 which has come under my notice. 



Carinopora Hindei (Nicholson). 



This being the only species of the genus, it is not needful 

 to recapitulate its structural characters, since these, so far as 

 known, have been fully discussed above. It only remains to 

 give the measurements by which the species is distinguished, 

 along with one or two characters which are not of generic 

 value. The only known specimen exhibits a portion of a very 

 large infundibuliform frond, which, though fragmentary, has 

 a height of four inches, with a diameter at the top of clearly 

 more than half a foot. The actual base is broken oiF. About 

 six brandies occupy the space of two lines. The fenestrules are 

 sometimes oval, sometimes hexagonal or polygonal ; and their 



