EUCRATEA. 1 1 



tions. In Scriqiaria clavata, Hincks, we have an inter- 

 mediate form, which connects the iiniserial and biserial 

 genera, and illustrates the way in which the one plan of 

 growth may have passed into the other. 



Throughout this family, so far as its British represen- 

 tatives are concerned, the zoarium is continuous or not 

 divided into segments by corneous joints. 



In defining the genera I have relied chiefly upon the 

 characters supplied by the differences in the aperture and 

 the mode of branching. If the number should seem to be 

 large for so small a group, I can only urge that it is not 

 more than sufficient to represent important modifications 

 of the family type. 



The family Eucratiidce includes the whole of the Gemel- 

 lariid(E of Busk, with the exception of the anomalous 

 genus Noiamia and Didymia (which last is distinguished 

 by a very different type of cell). The Australian genus 

 Dimetopia is allied to our own Gemellaria, and exhibits 

 an interesting modification of the back-to-back arrange- 

 ment of the cells. 



Genus EUCRATEA, Lamouroux. 



Der. From Eucrate, one of the Nereids. 



EucRATEA, Lainx. Biill. Soc. Pliilom. 1812 : Johnston : Smitt. 



ScRUPARiA, Oken, Lehrb. Naturg. Abth. ii. 90, 1813: Busk. 



Sertularia (part.), Linneeus. 



Cellularia (part.), Pallas. 



Cellaria (part.), Ellis and Solander. 



Unicellaria (part.), De Blqinv. Diet. Sc. Nat. 1830. 



Catexaria (part.), D'Orbigny, Pal. Fran5. 1850. 



Generic Character. — Zoarium composed of a creeping 

 adherent base and erect branching shoots. Zocecia sub- 

 calcareous, rising immediately one from the other, so as to 

 form a single series ; aperture large, oblique, lateral or sub- 



