28 EUCRATIID^. 



terminal, large, ivith the oral valve at the upper extremity ; 

 margin armed with spines. 0(ecia unknown. 



From Scruparia this genus is distinguished by its mode 

 of branching and its constantly vmiserial habit^ by its sub- 

 tubular cell, and large spinous aperture. From Huxley a it 

 is separated by the shape and structure of the aperture 

 and by its elongate subcylindrical cell. 



Brettia pellucida, Dyster. 



Plate TV. figs. 6, 7. 



BuETTiA PELLUCIDA, Di/stcT, Quart. Joiu-n. Micr. Sc. vi. (1858), 2G0, pi. xxi. 

 figs. 3-5. 



Zoarium perfectly transparent, about half an inch high. 

 Zocecia much elongated, subcylindrical, slightly ex- 

 panded towards the aperture ; aperture placed on the 

 front of the cell, at its upper extremity, oval, rounded 

 above, pointed below, with five to nine marginal spines, 

 irregularly arranged. Ooecia unknoAvn. 



Polypide with 10 tentacles. 



Habitat. On stone between tide-marks. 

 Locality. Tenby (Mrs. Brett: Dyster). 



Nothing is known of this minute but characteristic 

 form beyond what we learn from Mr. Dyster's brief de- 

 scription and Mr. Busk^s excellent figure, which I am 

 permitted to copy for this work. 



Brettia TUBiEFORMis. 



Plate II. fig. 2 ; Plate V. fig. 1. 

 Brettia pellucida, Norman, Rep. Brit. Assoc. 1866, 196 & 199. 



Zoarium minute, transparent, dichotomously branched, 

 surface smooth, attached bv a number of tubular fibres. 



