438 Prof. A. Schneider 07i the Structure 



possess vanes, but in a totally different order. In Veretillum 

 cynomormm (fig. 3) eight septa are present, and these are 

 differently constructed according to whether they stand upon 

 the left or the right half of the body. In the one half the vanes 

 are turned in the opposite direction to those in the other. 



How the calcareous lamellge of the corals constructed in 

 accordance with the number 6 originate has not yet been 

 investigated. Certainly they do not originate by the calcifi- 

 cation of the septa themselves ; but it is very probable that 

 they are produced in the inner space of each pair of septa. 

 When the number of lamellae does not exceed a certain limit 

 {e.g. in Galaxea)^ we may easily find individuals with only 

 six lamellae of the first order, then older ones with six of the 



Fig. 2. Fig. 3. 



second, and still older ones with twelve lamellae of the third 

 order. When more lamellaa make their appearance, the in- 

 crease takes place as follows : — In the space between a lamella 

 of the first and of the third, or of the second and of the third 

 order, a new lamella of the third order arises, the old lamellae 

 of the third and second order grow further and become lamellas 

 of the next higher order (namely, second and first) — for exam- 

 ple, in fig. 2, in which the sixth sector has enlarged and nearly 

 fjecome two new sectors. A new formation of this kind seems 

 to be capable of taking place in any sector. 



This very simple law of growth applies to all corals with 

 the number 6, although it is more difficult to ascertain in 

 such genera as Fungia &c., because, on account of the great 

 size and gradual growth of the lamellfe, these occur of very 

 different lengths. It has been tested on numerous specimens 

 of corals and on many figures of living and fossil corals, and 

 has always, without exception, been found correct. The well- 

 knoAvn very complicated law of Milne-Edwards and Jules 

 Haime can scarcely be verified, and is subject, as its inventors 

 themselves say, to numerous exceptions. It cannot pass as the 

 true expression of the facts. 



For the corals with the number S [c. g. the Rugosa) another 



