248 BULLETIN: MUSEUM OF COMPARATIVE ZOÖLOGY. 
might be two reasons for questioning my generic reference : the first is, I have 
not stated whether the synapticule are true or false. As no thin section was 
made, this point of structure could not be determined. But 1 do not believe 
in the systematic value of dividing synapticule! into true and false. Whether 
the synapticule are true or false depends largely upon spacial relations, as do 
many other microscopic features of the coral skeleton. If the septa are 
crowded the synapticule are apt to be false, while if they are more remote 
from each other the synapticule are apt to be true. Figure 71, in Miss 
Ogilvie’s “Microscopic and Systematic Study of Madreporarian Types of 
Corals,” 2? is a good illustration of this. This figure represents two adjoining 
septa of Siderastrea. Near the peripheral ends of the septa the synapticule 
are true, i.e. there are new calcification centers introduced to effect the junc- 
tion of the opposing septal granulations ; whereas, near the inner ends of the 
septa, where the opposing septal surfaces are close together, no additional 
centers of calcification are needed to make the junction of the granulations, so 
they fuse directly and form a pseudo-synapticula. 
Probably another note should be added on the septal structure. The trabecu- 
lar composition has already been noted. In the lower part of the calices the 
trabecular fusion seems perfect, but near the septal margins the fusion appar- 
ently may quite often be incomplete. Here pits are very distinct on the flat 
surfaces of the septa, should the septa be not completely perforated. This 
might be a second reason for the removal of the species from Mesomorpha. 
It was not determined whether dissepiments are present or not. 
Species of Mesomorpha occur in the Gosau Cretaceous and in the Eocene of 
the Arabian Desert. Pratz is of the opinion that Thamnastrea ferojuliensis, 
d’Achiardi, from the Italian Eocene, and Thamnastraa balli, Duncan, from 
the lower Eocene of India, also belong to this genus. 
DENDRACIS, Epwarps AND Haima. 
Dendracis cantabrigiensis, sp. nov. 
Plate XLI. Figs. 4-6. 
The corallum is composed of small slender branches from 3.5 to 8.5 mm. in 
diameter. The branch 3.5 mm. in diameter is 26 mm. long. There is no 
means of knowing to what length the thieker branches will attain. The 
calices are distributed in rather regular spirals ; the usual diameter is 1 mm., 
and the distance apart also usually 1 mm. On very small branches some 
calices may have a diameter very slightly less than a millimeter, and may be a 
1 Consult G. von Koch: “ Das Skelett der Steinkorallen,” Festschrift für Carl 
Gegenbauer, 1896, p. 260. 
2 Phil. Trans. Roy. Society, 1896, Vol. 187, p. 244. 
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