1889.] NATURAL SCIENCES OF PHILADELPHIA. 125 



muscle cells are more numerous and larger than elsewhere. Isolaia 

 presents similar structures. Zooxanthellse occur in the ectoderm of 

 the disc, and tentacles in both forms. The enclosures in the mesogloea 

 of the disc, which I thought might possibly be muscle cells in isolata, 

 are seen in Rusei to be comparable to the lacunae of the column wall. 



The mesogloea of the stomatodseum in both species of Gemmaria 

 has enclosures of granular cells (PI. VII, fig. 8), as a rule one such 

 enclosure opposite the insertion of each mesentery, especially in the 

 upper part of the stomatodseum, the arrangement being lost in the 

 lower part. The gonidial groove has the same shape as that of G- 

 isolata. 



The mesenteries are arranged in thirty-one pairs and are on the 

 microtypus. The mesogloea thickens towards the base so that the 

 basal canal is almost circular and not elongated as in G. isolata. 

 No reproductive organs were present. 



The description given by Duchassaing and Michelotti of Gemma- 

 ria Rusei, with which I identify this form, is very imperfect, but 

 so far as it goes it applies to the Bermuda species. The form de- 

 scribed by Gray 1 as Triga philipjnnensis is very similar in external 

 form and is in all probability a Gemmaria. 



Of the forms described above, no less than seven, viz : Condylaetis 

 passifiora, Phymanthus crucifer, Zoanthus fios-marinus, Mammillijera 

 tuberculata, Corticifera ocellata, C. glareola and Gemmaria Rusei, 

 are represented in the West Indian fauna, and of the other three, 

 the genera Aiptasia and Phyllactis also occur in the islands to the 

 South, leaving only the genus Diplaetis as a characteristic form of 

 the Bermudas. No doubt a systematic search for Actio ians in the 

 Bermudas would lead to the discovery of a greater number of West 

 Indian forms, but the proportion of common forms given above is 

 sufficient to show that the Actinian fauna of the Bermudas has been 

 derived from that of the West Indies. 



Explanation of Plates. 



£>c.=basal canal. en.— endoderm. 



c.—column wall. /r.=fronds. 



cm. =circular muscles. ?n.=margin. 



cw.— cuticle. ^).=tentaculiform fronds. 



d=disc. sp.=sphincter. 



1 y. E. Gray. Notes on Zoanthinse with descriptions of some new genera. Proc. 

 Zool. Soc. London. 1867. 



