580 
G. HERBERT FOWLER. 
lip, but in these forms, so far as I can ascertain, in natural 
contraction it is completely within the calyx. Further, as 
appears from his own researches and those of others on 
different forms, the whole skeleton, instead of being, as he 
describes, free in the coelenteron, is shut off from it by a layer 
of endoderm and mesoderm, and as much outside it as the rest 
of the corallum ; these layers he himself figures as clothing 
another part of the septum, though of this portion no histo- 
logical details are given. Yon Heider, in a paper shortly to 
be referred to, states that von Koch has overlooked the fact 
that the whole of the corallum is covered externally by ecto- 
derm and mesoderm ; certainly this form requires more com- 
plete investigation. Again, having ground many microscopic 
sections of corals I can afford no credence to “ sutures •” in 
the process cracks fly through the coral in all directions. But 
if evidence of a directly contrary character is needed, the case 
of Flabellum may be adduced, in which, according to Moseley 
(5), sutures run, not between the fused ends of the septa, i.e. 
through the theca, but down the centre of each septum. 
Though von Koch gives no detailed description of the anatomy 
of Carvophyllia, the following account may be inferred from his 
figures and text (4) (6). The polyp is built on the Actinian 
type, consisting of mouth-disc, stomodseum, mesenteries ; the 
muscles of the latter being arranged as in Actinia. No external 
body wall, its place being taken by the theca; inner body wall 
of mesoderm and endoderm, lining the coelenteron, aud clothing 
the interior of the calyx, both theca, aud septa. Mouth-disc 
drawn down in abnormal (?) alcoholic contraction over the 
lip of the calyx. Entosepta and exosepta both present. No 
mention made of tentacles. 
Of Madrepora variabilis he records, in 1880, the fol- 
lowing facts (6). Structure Actinian ; in the end-polyps of 
the colony six pairs of mesenteries, six entosepta, and six 
exosepta ; in the side-polyps also six pairs of mesenteries, but 
six entosepta only. 
V. Koch has also studied Stylophora digitata in some- 
what greater detail (7). The form of the colony resembles 
