ARACIINIDIUM FIBROSUM. 511 



ARACHNIDIUM FIBROSUM. 



Plate LXXI. figs. 0, 7. 



?ARACHIUDICV HIPPOTIIOOIDES (part.), Alder, Suppl. Northumb. Cat., Trans. 

 Tyues. F. C. v. pt. 3, 21 (sep.). 



Zocecia irregularly shaped, generally more or less ovate, 

 connected by short anastomosing fibres, which are given 

 off with much irregularity ; the margin of the cells set 

 round with very numerous fibrils or filiform processes ; 

 orifice long, tubular, projecting. 



THE most marked characteristics of this species are the 

 irregular form of the cells, and their numerous marginal 

 processes, and the long and prominent orifice. The con- 

 necting threads are generally short, and vary both in 

 number and position ; frequently several originate from a 

 cell. The margin of the zooecia commonly gives off a 

 number of very delicate fibrils, often of considerable 

 length, which spread out in all directions, and constitute 

 a kind of fringe. Sometimes the cells are united at the 

 extremities and form a continuous line ; occasionally they 

 are massed together ; but in its usual condition the zoarium 

 is a rude and irregular network. The tubular orifice is of 

 very considerable length, suberect, and prominent. 



HABITAT. On the tests of Ascidians and on shell. 



LOCALITIES. Lul worth Cove; ? Northumberland (Alder). 



