86 THE GENUS MONTICULIPORA. 



many Monticuliporoids, especially those which are referable to 

 Fistulipora, M'Coy, present a close general likeness to Helio- 

 lites; and It was not without considerable apparent reason that 

 Milne-Edwards and Halme regarded the FistuUporcs as refer- 

 able to the same group as Heliolites. The absence of pseudo- 

 septa affords, however, sufficient ground for the separation of 

 all the Monticuliporoids from the Helioporidce, at the same 

 time that the general likeness between the two groups is 

 strono'lv susfSfestlve of the existence of a real zooloo-Ical 

 relationship. 



It only remains to briefly compare the Monticuliporoids 

 with the singular Palaeozoic Polyzoan genera Ceraniopora, 

 Hall, and Hcterodictya, NIch. So far as the first of these Is 

 concerned, there is no difficulty in' separating even the en- 

 crusting species of Monticulipora as distinct, if we take those 

 forms of Ceramopora which, like C. inibricata, Hall, and C. 

 Hiironcusis, NIch., form very delicate parasitic expansions on 

 foreign bodies. In such cases, the colonies of Ceramop07'-a 

 are readily distinguished by the peculiar crescentic form of 

 the mouths of the tubes ; while I am not aware that they have 

 been shown to possess tabuke. On the other hand, there are 

 forms apparently referable to Ceramopora (such as C. Ohio- 

 ensis, NIch., and an abundant but undescrlbed species in the 

 Wenlock Limestone of Dudley), which, though primitively, 

 and generally permanently, encrusting, are nevertheless some- 

 times found to attain a considerable thickness, either by the 

 simple upward growth of the tubes, or by the superposition 

 of successive layers. Such forms may make a close approach 

 to certain of the Monticuliporoids in general aspect, and may 

 come to resemble the latter closely in their internal structure. 

 I hope to find a future opportunity of discussing the structure 

 of these peculiar types at greater length. In the meanwhile, 

 therefore, I merely figure their minute Internal structure (fig. 

 14), and make a few brief and general remarks. As above 

 noted, the general aspect of such forms Is not at all unlike 

 that of certain Monticuliporcr ; but even so far as this Is con- 



