12 EUCRATIID.K. 



terminal, the oral opening at the top of it ; branches given 

 off from the front of a cell beloiv the aperture. OCECI A 

 terminal. 



AVICULARIA and VIBRACULA wanting. 



TENTACULAR SHEATH terminating above in a ring of seise. 



THOUGH agreeing with Aetea in the character of the poly- 

 pide and the general plan of growth, the present genus 

 exhibits a very distinct type of cell. The composite habit, 

 whicli is rarely met with in the former (having only been 

 noticed in A. truncata] is the rule in Eucratea, which 

 also branches freely, and forms bushy plant-like tufts. 



The structure of the primary cell presents some inter- 

 esting peculiarities. Each colony of Eucratea commences 

 with a small zocecium, which is free (not adherent) and 

 borne on a short stalk, with a single joint in the middle 

 of it (Plate II. figs. 5-8). This stalk, however, does not 

 occupy the position of the usual peduncular portion of 

 the cell, but springs from the front surface, a little below 

 the aperture or area. It corresponds, in fact, with the 

 pedicle of a branch. The primary zooecium terminates 

 below in a short blunt process, which is perfectly free and 

 unattached. The produced peduncular portion, extend- 

 ing in the normal cell from the aperture downwards, is 

 not developed. The aperture occupies nearly the whole 

 length of the cell ; it narrows off to a point below, and 

 expands slightly upwards, being open at the top. The 

 upper extremity of the cell is subtruncate. From the base 

 of the stalk supporting this primary cell, in the specimens 

 which I have examined, another cell, decumbent and 

 adnate, is given off, which exhibits the normal shape, and 

 is attached to the parent zooecium by its lower extremity 

 (Plate II. fig. 7). It may be noticed in passing that there 

 is a striking resemblance between the primary cell of 

 Eucratea and the cell of Beania in an early stajro of 



