Poly zoa from Barents Sea. 281 



ESCHARA, auctt. 

 Eschara (auctt.) glabra, n. sp. (PI. XV. fig. 6.) 



Zoarium erect, having the zocecia in two layers, placed 

 back to back, dichotomously branched, the branches com- 

 pressed and slightly contorted. Zocecia arranged quincun- 

 cially with great regularity, ovate, surface smooth ; orifice 

 depressed, rounded above, lower margin straight, peristome 

 not raised ; the whole of the front of the zocecium (in the 

 adult state) covered by an avicularian cell, which is so closely 

 united to it, down the sides, as to appear, at first sight, an in- 

 tegral portion of it ; mandible terminal, prominent, overhang- 

 ing the orifice, much thickened, semicircular. cerium globose, 

 somewhat depressed ; surface smooth and shining. 



To understand the structure of this curious species, it is 

 necessary to study the zocecium in the earlier stages of its 

 development. When adult, and overlain by the avicularian 

 cell, it appears subcylindrical, well arched in front, with a 

 smooth, dense surface; but in its earlier stages the avicu- 

 larian cell is quite undeveloped, and its surface is somewhat 

 flattish ; a little later on the walls of the former may be 

 traced, rising on the front wall of the zocecium, which is ulti- 

 mately completely covered in and concealed. 



Every zocecium may be regarded as composed of two 

 chambers, one superimposed upon the other and closely 

 united to it. The true avicularium occupies the upper extre- 

 mity of the avicularian cell, is circular in form, and very 

 conspicuous. 



In the lower portions of the stem, calcification is carried to 

 a great extent, the orifices are deeply sunk, and much changed 

 in character ; in the basal region they are obliterated, and the 

 outlines only of the cells are faintly traceable on the sur- 

 face. 



Eschara perpusilla, a form described by Busk in his 

 account of the Polyzoa obtained on the last Arctic Expedition 

 under Sir G. Nares *, is evidently an allied species ; but in 

 this case the avicularian cell is only about half the length of 

 the zocecium. 



It may be necessary to constitute a new genus for the re- 

 ception of this species ; but further study of kindred forms is 

 necessary before it can be done satisfactorily, and meanwhile 



* Narrative of a Voyage to the Polar Sea during 1875-76 in H.M. 

 Ships 'Alert' and 'Discovery-' By Capt. Sir G. Wares. Vol. ii. Ap- 

 pendix, pp. 283-289. ^ 



