486 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
is represented by fragments of Theel’s species Synapta abyssicola , but 
there is enough of them to show that they should be marked as a variety, 
which may be called pacifica. 
Ccelentera. 
Development of a Palaeozoic Poriferous Coral.* — Mr. C. E. Beecher 
gives an account of Pleurodictyum lenticulare, a species which represents 
one of the simpler types of poriferous corals. The nepionic stage is 
well marked, and comprises the growth of the corallum to the comple- 
tion of a simple initial cell. In this stage there are no mural pores, and 
there is an epitheca over the entire exterior of the cup. The septal 
lines become developed towards the end of this stage. These features 
are in harmony with the young of many palaeozoic corals, and indicate a 
primitive, simple, and imperforate ancestry for the Perforata. The first 
nealogic stage, represented by the primitive co^allite with one bud, is 
the first transition towards both a compound and a perforate coral. At 
this stage we are reminded of Aulopora. The basal epitheca limits the 
fleshy portion of the organisms, and represents an area unfavourable to 
the acquisition of food, or for the natural development of calices. This 
would prevent both the maintenance of mural pores and the growth of 
basal buds. 
The author thinks that we may conclude that the mural pores in 
such genera as Favosites , Striatopora , Pleurodictyum , Michelinia , and 
others are ineffectual attempts at budding, resulting only in the perfora- 
tion of the cell-walls. As Yerrill has shown that the presence or 
absence of tabulae is of little or no importance in a natural classification, 
the non-tabulate nature of P. lenticulare is of no special consequence in 
a discussion of the relations of this species with Favosites or other 
tabulate poriferous genera. 
If Mr. Beecher’s views are correct a simple conical imperforate 
protocorallum may be assumed for the Madreporaria Perforata. The 
next stage has the structure and growth of Aulopora , and consists of the 
parent cell with one or more buds. Aulopora may, then, be con- 
sidered as representing a primitive type of a poriferous coral, in which 
the number of pores in each corallite corresponds with the number of 
buds plus one connecting it with the parent cell. It seems that, pr imarily, 
the development of mural pores is identical or homologous with the pro- 
cess of gemmation. 
Symmetrical Cell-development in Favositidae.f — Mr. C. E. Beecher 
is of opinion that the growth of intermural buds compensates for the 
natural divergence of the corallites. New cells are introduced wherever 
the old corallites have reached their maximum size, and when their 
divergence approaches a separation of the cell-tubes. The buds have at 
first the form of a triangular pyramid or prism, which is due to the 
mechanical conditions of growth. As they increase they touch or trun- 
cate one another, and change from triangular to five- and six-sided 
prisms. Completely symmetrical normal development produces a 
corallum with equal hexagonal calices. The process of intermural 
* Trans. Connect. Acad., viii. (1893) pp. 207-14 (5 pis.), 
t Tom. cit., pp. 215-9 (2 pis.). 
