FIXED MESSMATES. 63 



the Seychelles Islands by Mons: L. Eousseau. It is 

 not impossible that pinnotheres live in this same 

 tridacna, and that we have there a fresh example 

 of messmate within messmate. 



In the Bay of Massachusetts, on the coast of New 

 England, another curious messmate lives at great depths ; 

 Dana has lately described it, under the name of Epizo- 

 anthus Americanus, V. It establishes itself in the 

 Eupagurus pubescens. The Sertularia parasitica of the 

 gulf of Naples, from which I have formed the genus 

 Corydendrium, is a messmate after the manner of an 

 infinite number of other polyps. In closing this list, 

 we shall mention a polyp, named Halicondria suberea, 

 and the Actinia carcinopodus of Otto, which inhabit an 

 univalve mollusc ; as also the Heterosammise and the 

 Heterocyathi of the family of Turbinolidse, which lodge 

 in a trochoid shell. 



The sponges, placed by naturalists by turns among 

 plants or on the confines of the animal kingdom, are 

 now generally regarded as polyps; this is the opinion 

 expressed by Haeckel, who wishes at the same time to 

 replace the term Coelenterata by that of Zoophytes. 

 The learned naturalist of Jena, when making this pro- 

 position, should have remembered that in 1859 we 

 placed the sponges in the group of polyps, as the lowest 

 in the scale ; and that we proposed, from the time when 

 the acalephsB were recognized to be adult polyps, to 

 designate all these animals under the name of Polyps. 

 Some time after, E. Leuckart proposed the appellation 

 Ccelenterate Polyps, which has been generally received. 

 Professor Haeckel would have lost nothing by acknow- 

 ledging that in 1873 he arrived at a result similar to 



