111 
Fenestellide. The most anomalous point is the position of the cells, or rather their mode of 
opening on the surface. The frond is funnel-shaped, and the cells open towards the interior of 
the funnel, as in Retepora. Towards the upper portion of the frond, the cells seem to open 
simply at the bottom of the deep grooves between the internal keels, and the fenestrules open 
into the same grooves, and there is, therefore, no special difficulty here, if, as seems tolerably 
certain, the keels are not here connected by an imperforate connecting membrane, and the 
grooves thus remain open to the access of sea-water ; near the base, however, the keels are 
clearly connected internally by a membrane which has no perforations in it, and the deep 
intervening grooves are filled up by a vesicular calcarous 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 polyzoary may perhaps have been gradually 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 be not the case, I cannot explain the 
undoubted facts. 
The enormous internal keels, whether free or connected together internally give an extra- 
ordinary depth and thickness to the polyzoary, and the fenestrules do not extend to more than 
about a fourth of this depth, nor do the cells. In Hemitrypa (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 
Cryptopora (Nich.) again, the outer and inner surface of the polyzoary are both imperforate, 
aud the cells open internally into a central space which is crossed by recularly-placed pillars, 
haying 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 :— 
134. CARINOPORA HINDEI (Nicholson). 
Carinopora Hindei (Nicholson), Annals of Natural History, Feb. 1874. a 
This being the only species of the genus, it is unnecessary 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 charae- 
ters 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 above of clearly more than half a foot. The actual base is broken off. About six 
branches occupy the space of two lines. The fenestrules are sometimes oval, sometimes hex- 
agonal or polygonal, and their arrangement differs in different parts of the frond. Sometimes 
they are arranged in regular diagonal lines ; but even in this case there are often percep- 
tible central longitudinal lines, on either side of which the diagonal rows of fenestrules diverge 
in opposite directions, like the barbs of a feather, giving rise to a most peculiar appearance. 
At other times the fenestrules are rhomboidal, hexagonal, or polygonal, and are not arranged 
in distinet diagonal rows ; whilst two contiguous longitudinal rows are often separated by an 
unusually narrow and apparently quite straight branch (See Fig. 48 c). The spaces along 
which the flexuous branches inosculate have a depth of about half a line, considerably exceed- 
ing the width of the branches ; so that whilst seven fenestrules occupy a quarter of an inch 
measured diagonally, only four occupy the same space measured longitudinally. The thick- 
ness of the frond, measured at right angles to its plane of growth, is one line or a little more, 
nearly two-thirds of this being accounted for by the great internal keels, Lastly, there are 
generally three cell-mouths to the length of a fenestrule, with two placed opposite the inoscu- 
lation of each pair of contiguous branches. 
The only known example of this singular species was discovered by my friend, Mr. 
George Jennings Hinde, by whom it was submitted to me for examination, and in whose 
honour I have named it. 
Locality and Formation.—Corniferous Limestone, Jarvis, County of Walpole. 
Genus CLATHROPORA (Hall). 
Polyzoary composed of membranous flattened expansions, which either branch without 
anastomosis, or, more typically, divide into branches which inosculate at short intervals till 
there is produced a broad frond perforated at regular intervals by rounded or oval fenestrules 
