GENERAL HISTORY. 13 



in justice to Dybowski, it must be stated that he has founded 

 his Diamdites, not upon the later definition of this genus given 

 in the ' Lethsea Rossica,' but upon the earHer definition given 

 by Eichwald in the ' Zoologia speciaHs ' (vol. i. p. 180, 1829). 

 It is really not worth while taking up space with reproducing 

 from Dybowski's work this earlier definition, which Dybowski 

 justly speaks of as " diese nichtssagende Charakteristik." I 

 will only notice, that the definition might apply to a score or 

 more of known genera of Corals or Polyzoa, with equal pro- 

 priety, as it does not include a single character of generic value ; 

 and that there is certainly no mention in it of the " spongy 

 coenenchyma" so strongly insisted upon in the later definition. 

 At the same time, provided that, as in this case, no other 

 observer has in the interval meddled with the genus, it is 

 surely only reasonable to take an author's latest and e^nended 

 definition as the basis for further and better investigation, 

 rather than his earlier diagnosis. 



Lastly, Eichwald defines Montiailipora^ D'Orb. (Lethaea 

 Ross., p. 492), as comprising forms with a semiglobose, ovate, 

 or depressed corallum, the surface of which is covered with 

 small elevations, while the base is flat and concentrically 

 striated. The corallum is said to be composed of delicate 

 tubes alternating with fascicles of larger corallites, with round- 

 ed calices, and the walls furnished with minute irregular com- 

 municating pores ; while there are horizontal and close-set 

 tabulae. It is not necessary to discuss this definition, as the 

 only species which D' Eichwald places under it {M. ovuhim, 

 Eichw.) appears to be undoubtedly a Heliolites, or, at any 

 rate, to belong to the Hcliolitidce. 



The next important contribution to our knowledge of the 

 Monticuliporoids was a memoir by Dr Rominger, entitled 

 " Observations on Cheetetes and some related Gen- 

 era, in regard to their Systematic Position ; with an 

 appended Description of some New Species" (Proc. Acad. 



mate to a fulfilment of this last essential condition, and, in my opinion, ought to be 

 unhesitatingly rejected. 



