vine: paleontology of the wenlock shales. 
237 
colonies, only that they are small . Adherent to a fragment of Halysites 
is a young colony of Heliolites. The primary corallite is rather long 
and pointed at the proximal extremity. At about half-a-line from 
the point is the first calicular cup. It appears that the first corallite 
is produced by gemmation (?) from the primary, then the secondary 
produces another corallite latterly, which is the cause of the first 
increase in the width of the colony. Many of the free fragments in 
the shales clearly show that the first stage in the growth of the colony 
was parasitic on some other fossil. 
13. Heliolites megastoma, M'Coy. Edw. & H., Brit. Foss. Cor., 
p. 251. 
Fragments of this coral are present in the washings, and the two 
species are easily distinguished when compared together, the calicos 
being more closely set in one than in the other species. 
14. Callopora nana, Nicholson. Ann. Mag. Nat. Hist., 1884, 
p. 120, pi. vii., figs. 4-4b. 
This beautiful species was originally described by me in a paper 
sent on for reading to Professor Duncan, Dec, 1882, but not pub- 
lished, as Monticulipora fistulosa, but as my original description 
contains a few particulars not noticed by Professor Nicholson, I make 
no scruple in adding to his description, especially as my own diagnosis 
was drawn up from hundreds of specimens from the Buildwas beds. 
Corallum, in its earliest stages encrusting, after which it assumes 
a globose, oblong, or an iiTegularly branching shape. Corallites large 
and small in its earliest or encrusting stage, the small corallites cover 
as a delicate fihn some foreign body; if the object should be circular, 
then future developement of the colony will be either a small pill- 
like globe, or a delicate stem, and the shape of the future colony is to 
a large extent dependent upon the shape of the object which it 
originally encrusts. In this early stage also all the smaller corallites 
are either oval or oblong, with circular corallites interspersed here 
and there. After about the space of a line, more or less, clusters of 
larger corallites make their appearance, surrounded by smaller ones; 
then again maculae of the smaller groups intervene between normal 
corallites, which may always be distinguished by their circular 
character. Calicos, occasionally covered with an opercula, which may 
