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SUMMARY OF CURRENT RESEARCHES RELATING TO 
it is now more than thirty years ago since Lacaze-Duthiers made the 
sole examination of its anatomy which we have. Mr. Carlgren finds 
that Gerardia is not an Antipatharian at all, but a Zoanthid, and that 
it closely agrees in anatomical structure with the genus Parazoanthus. 
The ccenenchym ordinarily forms a thin layer over the horny axis, being 
thickened at places where there are connections between the branches of 
the colony. The number of tentacles was found to be generally 26 or 28, 
though occasionally 24 were found, as in the examples investigated by 
Lacaze-Duthiers. The number 28 agrees with the arrangement of the 
septa. The ectoderm is distinct, though not as thick as the mesogloea. 
In the former there are sometimes found incrustations consisting of sand- 
grains, sponge-spicules, Foraminifera, and the calcareous corpuscles of 
Gorgonids. Very rarely diatoms are found. As the mesoglcea consists 
of a homogeneous intermediate substance with more or less distinct con- 
nective tissue-cells, it resembles that of Parazoanthus. In addition 
there are ectodermal lacunae and an encircling sinus in the distal part of 
the body. These recall the figures which Haddon and Shackelton have 
given of Parazoanthus dixonii. The circular muscles of the internal 
surface of the mesogloea are feebly developed, and in the distal part 
there is an endodermal sphincter. In the tentacles and in the oral disc 
the muscles are also feebly developed. The oesophagus consists largely 
of supporting cells. It is continued into a conical tube which contains 
only the thickened part of the mesogloea, and is only connected with 
the body-wall by the complete pair of directive mesenteries. The 
mesenteries themselves were developed as in the Zoanthids, and they 
agree in arrangement completely with the “ macro-type.” The author 
has not been able to find the arrangement of ^4 septa described by 
Lacaze-Duthiers, nor are all the mesenteries complete as the figures of 
that author would lead us to suppose. The macro-mesenteries in the 
distal parts of the body are much thicker than in the more proximal, 
and the same appears to be true of the micro-mesenteries. Gonads were 
found in one individual only ; they belonged to the female, and as is 
ordinarily the case in Zoanthids, they were developed only on the com- 
plete mesenteries. It would appear probable that not only the separate 
individuals in the colony are of separate sexes, but that each colony 
produces only male or female generative products. If this be so the 
genus exhibits here another point of agreement with Parazoanthus . 
Although the author speaks with reserve in consequence of the poverty 
of his material, he is inclined to think that the canal system is not 
arranged so regularly as Lacaze-Duthiers draws it. Sections of the 
horny skeleton show that it is made up of numerous concentric layers, 
but in consequence of the pressing together of the layers the arrange- 
ment is often very irregular. The small crateriform elevations figured 
by Lacaze-Duthiers are nothing more than small undeveloped polyps. 
The author gives a complete history of the views which have been held 
by various writers as to the systematic position of this interesting genus, 
and concludes with offering a diagnosis of Gerardia which runs as 
follows : — Zoan these with the mesenteries arranged after the macro-type 
form (macrocnemic Zoantheee); sphincter diffuse, endodermal; body- 
wall encrusted ; the ectoderm is continuous ; the mesogloea contains 
ectodermal canals, cell islands, and an encircling sinus. The coenen- 
