20 RECORDS OF THE AUSTRALIAN MUSEUM. 



The following is a description of the genus and species : — 



Genus Mictocystis, 2 gen.nov. 



Gen. Char. — Corallum compound-cystiphylloid, coarse vesicular 

 tissue enveloping disconnected cylindrical corallites, without 

 proper walls. Septa lamellar, confined to visceral chambers, not 

 impinging on the vesicular tissue. Tabulae usually complete. 



MlCTOCYSTIS ENDOPUYLLOIDES, Sp.UOV. 



Sj>. Char. — Corallum of large size, consisting of a mass of large 

 lenticular vesicles enveloping unequally spaced-apart corallites; 

 surface convex and slightly blistered. Corallites long, cylin- 

 drical, with an average diameter of ten millimetres. Calices 

 moderately deep, more or less crateriform at the surface; sides 

 inclined, blistered. No evidence of proper walls or inner mural 

 investment to the corallites (visceral chambers). The latter are 

 surrounded by the vesicular tissue, which is highly developed and 

 composed of large blister-like, arched, inwardly inclined vesich s 

 of different shapes and unequal size, but the lenticular predomin- 

 ating. Septa well developed in and confined to the visceral 

 chambers as simple vertical lamella?, of one order, and to the 

 number of about twenty-four, extending almost (if not quite) to 

 calicinal centre, but without mingling or revolving, and neither 

 passing over the surface blisters nor extending on to those 

 forming the spurious walls of the visceral chambers. Tabula) 

 horizontal, close, slightly bent downwards at their peripherics. 



Loc. — Junction of Spring and Cap Creeks, Portion 98, Parish 

 Barton, County Ashburnham (C. A. Siissmilch — Colls. Australian 

 Museum and Sus.smilch). 



//or. Upper Silurian, Halysites Limestone (Bed A of -Mr. 

 Siissmilch's section 3 ). 



2 fiiKTos = compound ; kv<ttis-& bladder or vesicle. 

 Siissmilch — Journ, Roy. Soc. X. S, Wales, xl., 1907, p. 131, pi. xix. 



