PALAEOZOIC CORALS AND FORAMINIFERA. 99 



their resemblance to Heliopora. The distinct walled tubular cells 

 visible in both sections, connected by cellular tissue, with their 

 twelve rudimentary lamellae, distinguish the present ancient corals 

 from the modern genera just named, for Porites has a minutely 

 reticulated corallum impressed by shallow polygonal undefined 

 cells on the upper surface, and presenting in the horizontal and 

 vertical sections an uninterrupted uniformly vesicular structure. 

 Heliopora agrees perfectly in external appearance, and in the 

 two sections exhibits the same characters of vesicular structure 

 connecting tubular cells with transverse diaphragms, but in it 

 the tubes have eighteen or more rudimentary lamellfe, while 

 they are constantly twelve in the present genus, which I only 

 know as yet in the older and middle palaeozoic rocks. 



Fistulipora (M^Coy), n. g. 

 Gen, Char. Corallum incrusting, composed of long, simple, cylin- 

 drical, thick-walled tubes, the , 

 mouths of which open as simple (^ky-^^ ^ ^^L^ 

 equal circular cells on the sur- ^^^^^^^fe^ fe^S 

 face, and having transverse ff^^pJ^^S ^pS-| 

 funnel-shaped diaphragms at ||^^P^T 1^ 

 variable distances ; interval be- tM.^^M«L^ 

 tween the tubes occupied by a Fistulipora : a. mode of growth, nat. 

 cellular network of small vesi- size, enveloping a crinoid stem. 

 cular plates. ^' magnified surface and section. 



This genus is proposed to include the Manon cribrosum (Gold.) 

 of the Eifel, &c., and the two following species from the moun- 

 tain limestone. They have no affinity with the fossil sponges of 

 the genus Manon, with which the only previously known species 

 was classed by Goldfuss and others, but are more allied to the 

 so-called Porites of the palaeozoic rocks {Palceopora, M^Coy), 

 from which they differ in the absence of the rudimentary radia- 

 ting or vertical lamellae to the cell-tubes. The sides of the tubes 

 do not seem to be ever perforated by connecting pores. 



Fistulipora minor (M^Coy). 

 Sp. Char. Cell-tubes with slightly prominent margins at the 

 surface, about four in the space of one line, rather less than 

 their own diameter apart, the intervening space composed of 

 from one to three rows of the minute vesicular cells. 



, The tubes of this species are of so small a diameter that I have 

 not been able to see the diaphragms ; they are from half a line 

 to nearly an inch in length according to the age of the example, 

 but not altering materially their diameter or relative distance. 

 It most usually occurs incrusting crinoid stems or other foreign 

 bodies, from which the tubes radiate to the surface, and I suspect 



g2 



