COMPARATIVE ANATOMY OF SOME RRITISII ACTINLE. 545 



except in a narrow ring at tlie upper margin of the body was entirely 

 replaced by a light flesh colour. Andres' specimen possessed a brilliant 

 metallic iridescence. 



In all the paler varieties the animal becomes translucent when ex- 

 panded, so that the septa and vermiform filaments may be seen through 

 the body-wall. This is evidently an example of albinism. The animal 

 changes its form very o|ten, at one time it will assume the appearance of 

 a slender cylindrical stem, fixed by one extremity and bearing on the 

 other extremity a flattened disk. Sometimes a contraction will take 

 place in the middle of the body so as to cause the animal to present some- 

 what the appearance of an hour-glass. In assuming its many different 

 forms the stomatodaeum is never everted. 



Allman found two concentric rows of tentacles arising near the margin 

 of the disk, but the number and arrangement is variable. They are 

 tubular like the tentacles of other Actiniae and communicate freely 

 with the interseptal spaces. They are imperforate at the apices, which 

 are very much swollen. 



I have examined specimens of C. viridis chiefly with the aim of com- 

 paring it anatomically with the Australian specimens, which are the only 

 Corynactids well known in this respect. 



Anatomy and Histology : — 



The ectoderm of the column wall is fairly spongy in places, in other 

 places it is like that of C. myrcia, described by Duerden, and consists of 

 large unicellular gland cells mingled wdth narrow supporting cells. The 

 gland cells become swollen near the free surface, where in places they give 

 rise to a clear zone. The contents of these cells are usually clear, and then 

 they do not take stain easily but stand out as highly refractive bodies. 

 In other cases they become deeply stained because the contents are 

 granular. 



The nuclei of the ectoderm cells are deeply stained, and as in C. hopUtes 

 and C. myrcia they are arranged in a zone a little within the middle of 

 the ectoderm layer. 



The interior part of the layer forms a clear zone, this marks the posi- 

 tion of part of the nervous system. The ectodermal muscle can be dis- 

 tinguished at the base of the ectoderm. The body-wall of the pedal disk 

 is fully expanded, and therefore appears very narrow as compared with 

 that of the column. The ectoderm of the base appears to be one-fourth 

 of the thickness of that of the column wall. In this region the ectodermal 

 muscle is very strong and thick processes of mesogloea can be seen 



