CARBONIFEROUS FOSSILS OF IRELAND. 205 



Hemitrypa Hibernica. Sc. sp. (PI. XXIX. fig. 7). 



Fenestella Hibernica. Scolder, MSS. 



Sp. Ch. — Polymorphous, irregularly conic; internal net- work having the interstices equidistant, straight 

 fenestrules equal, oblong, rounded ; length rather less than twice the width ; dissepiments tliinner than the in- 

 terstices ; internal non-poriferous face rounded, smooth ; external poriferous face angular ; pores small, oblong, 

 (not prominent ?) about three to the length of a fenestrule ; external sheath nearly smooth, marked externally 

 ^v^th faint, equidistant stria-, which coincide with the interstices of the internal net- work, and enclosing between 

 them two alternating rows of large, rounded, or obscurely hexagonal depressions, coinciding with the openings 

 of the internal net-work. 



This curious coral throws much light on the structure of Professor Phillips's genus Hemitrypa. The in- 

 ternal net-work bears much resemblance to the F. memhranacea, Phil., but from the difficulty of procuring 

 well-preserved specimens of this latter, it is difficult to determine the question satisfactorily ; in the present coral 

 however, the fenestrules seem to be generally shorter in proportion to their length ; the dissepiments thinner ; 

 and the obverse either smooth or (in some specimens from shale), with large, irregular, distant, spiniform tu- 

 bercles, but never granulated in the minute and regular manner of the F. memhranacea. 



• Hemitrypa oculata. Phil. 



Hemitrypa oculata. Phil. Pal. Fos. 

 I have referred with hesitation to this species, some fragments, belonging evidently to the genus 

 Hemitrypa, but distinct from the H. Hibernica; they are much smaller in their details than that species, 

 and approach more nearly to Professor PhilUps's figures of the H. oculata ; the openings in the external sheath 

 are small and round, as they are figured and described in that species, differing remarkably from the large, 

 hexagonal ones in the H. Hibernica; the interstices also of the internal network are oval, as in the Devonian 

 species, while in the former one they are square ; the specimens, however, are not good enough to define the 

 species properly. 



ICHTHYORACmS. M' Coy. 



Gen.Ch. — Coral plumose, composed of a straight, central stem or midrib, having on each side a row of short, 

 simple branches or pinnai, all in the same plane ; obverse both of the midrib and lateral branches rounded, with- 

 out keel, and each bearing several rows of small, prominent, oval pores, arranged in quincunx ; reverse rounded, 

 smooth, or finely striated. 



The present genus stands nearly in the same relations to Glauconome, Lons., as Polypora, M'Coy, does to 

 Fenestella, Jliller. Fenestella and Glauconome are carinate on the obverse, and bear two rows of large, pro- 

 minent pores, while Polypora and Ictlujorachis are rounded on the obverse, and bear several rows of small 

 pores arranged in quincunx. It is probable that this is the fossil alluded to by Mr. Miller, when he quotes ver- 

 tebra of fishes in the Cork limestone, no bony fishes occurring in those formations, and the coral very 

 strongly resembling the spine of a small fish ; I have named the genus from this resemblance l\Qv^ a fish, and 

 pdx(C) a back-bone. 



ICHTHYORACHIS NeWENHAMI. M'Coi/. (PI. XXIX. fig. 8). 



Sp. Ch. — Stem and lateral branches with five rows of oval, prominent pores, closely arranged in quincunx ; 

 reverse flattened, slightly convex, divided by a deep groove along the middle ; obsoletely striated longitudi- 

 nally ; lateral branches half the thickness of the midrib, space between them equal to the diameter of the 



midrib. 



3F 



