196 HYATT, 



Finally, so mauy buds are produced simultaneously, 

 that they crowd themselves together in quincunx order, in- 

 stead of forming distinct radiatory branches, as they would 

 do if developed singly or in pairs at intervals, the whole 

 being a greatly distended primary cell or coenoecial trunk. 

 This view is sustained by the occurrence of the buds upon 

 the border in the same place, with relation to the poly- 

 pides of Cristatella, that they occupy in the single cells 

 of Fredericella and Plumatella, and in the lobes of Pec- 

 tinatella. 



Irregularly divided by permanent interned folds of the 

 endocyst. These folds are, present more or less in nearly 

 every colony of Fredericella and most of the difi'usely 

 branching Plumatellas, but not in the Alcyonelloid varie- 

 eties. I suspect, however, that variety b of Plumatella 

 vitrea, has them. If so, they probably act as in Lopho- 

 pus. and isolate the branch in which they occur. 



The peculiar aspect of the constrictions in Plumatella, 

 bending inwards from the stiff ectocyst and apparently 

 prevented from coming together by its unyielding nature, 

 their accidental occurrence in any part of the branch, and 

 their being simply an annular constriction of the endocyst, 

 all go to prove, as has been shown in the article on re- 

 production, that they are the homologues of the constric- 

 tions that divide and multiply the coenoecia in Pectinatella 

 and Cristatella. 



ECTOCYST. 



Thin. The Fredericellse all have thin ectocysts. 



There is a variety of Fredericella Regina, and one spe- 



. cies, F. pulcherrima, which have colorless ectocysts, but 



these are not thicker than the horny coverings of the 



other varieties. 



The Plumatell93 have thin ectocysts, except in P. vit- 

 rea. In this they are somewhat thicker than in other 

 species. In Lophopus it is very thick below, indicat- 

 ing the final withdrawal of the whole under the coence- 

 cium in Pectinatella. Its immense thickness, in the last 

 genus, is directly caused by the surface of attachment 



