to Micro-Paleontology. 119 
form, and not rather to the very similar /. dudensis, which 
I shall describe immediately. 
If, however, Lonsdale’s title is to be retained, it is best to 
keep it for the form which has been usually regarded by 
observers as Heteropora crassa. ‘There is no doubt as to the 
propriety of the reference of this form to Fistulipora, M‘Coy, 
as shown by the in general complete isolation of the corallites, 
and the fact that the walls of the interstitial tubules are so 
imperfect as to allow of a confluence of their tabule, and the 
consequent production of an intermediate vesicular tissue. 
Fistulipora crassa is most nearly allied to &. ludensis, Nich., 
from which it is distinguished by its not forming thin crusts, 
by the generally projecting mouths of the corallites and their 
larger size, by the larger size and smaller number of the 
interstitial tubuli, as well as by their incomplete walls, and, 
lastly, by the want of “ spiniform tubuli.” 
Formation and Locality. Wenlock Limestone, Dudley, 
Benthall Edge, Dormington. 
2. Fistulipora ludensis, Nich. (Pl. VII. figs. 3-3 0.) 
The corallum in this species forms thin crusts, from half a 
line to three quarters of a line in thickness, growing upon 
foreign objects. ‘The surface is smooth, without definite 
macule or monticules, and exhibits the circular openings of 
the ordinary corallites, surrounded by very numerous minute 
interstitial pores. As seen in tangential sections (Pl. VII. 
fig. 3), the corallites are seen to be circular or oval, often 
indented at one point, or at two points, and about 4; inch 
in diameter. ‘The corallites are in general completely isolated, 
and are separated by one, two, or three rows of very minute 
interstitial tubuli, which are subpolygonal in shape, and have 
tolerably complete walls. As just mentioned, the wall of the 
visceral chambers of the corallites is often bent inwards on 
one side or at more than one point, and at such points “ spini- 
form tubuli” are usually developed (Pl. VIL. fig. 3a). Simi- 
lar spiniform tubuli may also be sparingly developed among 
the ordinary interstitial tubuli, As seen in long sections 
(Pl. VII. fig. 36), the corallum is seen to be built up of suc- 
cessively superimposed thin strata of tubes. The proper 
corallites are crossed by a few remote, complete, horizontal 
tabule ; while the interstitial tubules have more closely set 
tabule, which are so disposed as to give rise in the longitudi- 
nal section to a sort of vesicular interstitial tissue. 
The present species is in many respects very similar to 
Fistulipora crassa, Lonsd., sp.; and it is quite possible that 
Mr. Lonsdale may have had this form, at any rate partly, in 
