FOSSIL INVERTEBRATED ANIMALS. 517 



immense masses aforesaid, which they form in the Southern 

 Ocean. 



Linnaeus was the first naturaUst who deemed it proper to 

 separate from the madrepores^ under which name, before his 

 time, all the stony polyparia had been confounded, a consi- 

 derable number of species, which are distinguishable, at the 

 first glance, by the smallness of the pores, or polypiferous 

 cellules. M. Lamarck has made two or three alterations in 

 the arrangement and situation of the MiLLEPORiE, not necessary 

 to be mentioned here. 



Donati, and especially Cavolini, have given us some details 

 on the animals of the true millepores ; but we must here con- 

 fine ourselves to their habitation. This consists in lodges, or 

 simple cellules, oval, with a very small rounded aperture; 

 these form, by their accumulation and intimate union from 

 bottom to top^ a calcareous polyparium, with branches nearly 

 round, of equal diameter, irregular, and sometimes truncated 

 at the extremity; and, at other times, in the form of subcrus- 

 taceous or foliaceous expansions. They exist in all seas, but 

 more especially in those of the hot climates. 



It may be generally affirmed that the fossil remains of marine 

 genera, whose species inhabit the existing seas, are more usually 

 found in the tertiary strata than in those which are more 

 ancient ; but this is not the case with the millepores. Although 

 their species are tolerably numerous in the living state, no 

 remains of them appear to have been hitherto found, except in 

 the strata anterior to the chalk, or in the lowest of that sub- 

 stance. A great number have been found in the environs of 

 Caen. 



To pursue any further these notices of families and genera 

 of invertebrated fossils would lead us far, indeed, beyond the 

 limits to which this essay must of necessity be confined. For 

 the incompleteness of our sketches, those hmits, and the im- 

 mensity of the subject, must plead our excuse ; at the same 

 time, though none can be more conscious of the general defi- 



