386 Say on Shells, &c. 
the latter has been taken for Basalt, and M. Lamarck when 
describing it, inquires “Est-ce un polypier?” | Madrepora 
fascicularis, of Volck. and Parkin. in common with F. striata 
and F. Gothlandicum, is distinguished by the transverse septa, 
a Character which induced me to refer the species here de- 
scribed to Favosite ; they seem therefore to be congeneric, as 
‘analogy indicates a participation in the character of osculated 
paries. 
Amongst the great variety exhibited by this species, we have 
to remark more particularly the following, viz. : 
Ist. Alveoles perfectly free, that is, destitute of aciculi 
or lamella, the septa wanting, and sometimes the osculi ob- 
solete. 
2d. Alveoles filled almost to the summit with the septa, and 
resembling those combs of the bee-hive which are filled with 
honey and covered over. 
3d. Paries beset with very numerous, interrupted, alter- 
nating, transverse lamelle, which are denticulated at their 
tips, and project towards the centre with various degrees of 
prominence and irregularity. 
The first variety corresponds with the generic character, 
and the third approaches the genus Porites; yet so unequivo- 
cally identical are they, that I have seen them all united in 
€ same mass and perforated throughout by the osculi. The 
identity is further obvious by the perfect gradation which 
renders them inseparable. 
With respect to the transverse septa, I think their presence 
may be accounted for by supposing that as the animal elongates 
its tube in consequence of an increase of growth, or in order 
to maintain an equal elevation with the adjacent tubes, (ren- 
dered necessary by the origin of young tubes in the interstices) 
it gradually vacates the basal portions of its tube, and sustains 
itself at the different elevations, by successively uniting the 
parietal lamelle so as to exclude the vacuity. ‘That this is pro- 
bable, we may infer from a similar procedure on the part 
of several species of testaceous mollusca. ‘Thus some Lin- 
nzan Serpula become camerated, and a familiar instance pre- 
sents itself in the Triton tritonis, the animal of which adds suc- 
