EUPLECTELLA. 37 



EUPLECTELLIDiE. 



Under this family tlie forms studied by me are as follows : 



1. Euplectella imijerialis Ij. 5, Regadrella ohinoseana Ij. 



2. E. marshaUi Ij. 6. R. komeyamai ii. sp. 



3. E. owenl Herkl. & Marsh. 7. ?i^. phoenix O. Schm. 



4. E. curvistellata n. sp. 8. Walteria leuchai^ti I J. 



In the present contribution I propose to give in detail the 

 results of my investigations in regard to these genera and species. 

 In so doing I shall freely advert to questions of a more general 

 bearing in order to make clear my own points of view. 



Euplectella Owen. 



I will let a summary account of the organization of the 

 genus in general precede the special descriptions, since in this 

 way many of my views can be dealt with once for all. I have 

 also considered it necessary to connect therewith some explanatory 

 remarks on the terminology adopted. Should this method make 

 the account of the genus somewhat lengthy, I may be excused 

 therefor on the ground that a corresponding curtailment will be 

 thereby made possible in the later pages. For detailed statements 

 of many of the facts in support of my generalizations the reader 

 is referred to the descriptive sections. 



General structure. — I regard Euplectella to be derived 

 ontogenetically and phylogenetically from a primitive form with 

 these characteristics : A thin-walled tubular body, macroscopically 

 closed on all sides except on the upper terminal surface, where 

 is found a close aggregation of openings, the oscula, which put the 



