lo THE GENUS AIONTICULIPORA. 



to some extent uncertain, till it may be possible to examine 

 microscopically the original specimens upon which Milne- 

 Edwards and Haime founded their determinations. 



In 1859, Mr Billings described (Canad. Nat., vol. iv. p. 

 427) some species oi Monticulipora from the Silurian rocks of 

 Canada, referring these to the genus Stenopora, Of 

 the forms in question, two {S. patula and S. adhcBvens) 

 are described as new species ; but the descriptions given are 

 so vague and so brief, that it would be impossible to recognise 

 their validity until the original specimens can be re-examined 

 and described. 



In i860, D'Eichwald published the first volume of the 

 ' Lethaea Rossica,' in which various forms of Monticulipora were 

 described. These were referred to the o-enera CJicb- 

 tdes, Fischer, Dianulites, Eichw., Orbipora, Eichw., 

 and Monticulipoi^a, D'Orb., and possibly to one or two other 

 genera (such as Myriolithcs). As the attempt has recently 

 been made by Dybowski to resuscitate the genera DianuliteSy 

 Eichw., and Orbipora, Eichw,, it may be as well to supply here 

 a brief analysis of the account which D'Eichwald gives of the 

 above-mentioned four genera, and of the forms which he in- 

 cludes under them. In so doing, I may premise that much of 

 this portion of the ' Lethaea Rossica ' was really published by 

 Eichwald in the ' Zoologia specialis' (1829), to which, unfor- 

 tunately, I have not access. At the same time, the ' Lethaea 

 Rossica' contains the matured views of Eichwald as to these 

 and other genera, and it seems only fair to take an author's 

 emended diagnosis as the basis for any criticism of his views : — 

 With reeard to the eenus Chcetetes, Fischer, Eichwald recoe- 

 nises that it is separated from Monticulipora, D'Orb., by its 

 fissiparous mode of development, and he places under this 

 head eight species — viz., C. heniisphcBricus, Eichw., C. pyri- 

 f or mis, Eichw., C. apiculatus, Eichw., C. anmilatus, Eichw., C, 

 fastigiatus, Eichw., C. cylindraceus, Eichw., C. radians, Fisch. 

 and C. tumidns, Phill. With regard to the great majority 

 of these, it is quite within the mark to say that it would be 



