316 



Escharella diaphana Mac Gillivr. 



Lepralia diaphana Mac Gillivr., Mac Coy, Prodromus of the Zoology of Victoria, 



Vol. I, Decade IV, p. 22, PI. 35, fig. 3. 



(PI. XVII, figs. 1 a-1 d). 



The zooBcia, which usually have a rounded rhombic form, are rather strongly 

 arched, thin-walled, smooth and surrounded by raised lines, which end on each 

 side at the inner part of the frontal spine. While these raised lines (formed by 

 the free continuation of the lateral walls) in the proximal half of the zooecium 

 are very low and separated from the arched frontal wall by a groove, in which 

 a number of marginal pores can be more or less distinctly seen, they are very high 

 in the distal half (provided with the pore-chambers), and here they lie close up 

 to the lateral part of the frontal wall with which they partly coalesce, in such 

 a manner that each marginal pore opens out on the frontal wall through a canal, 

 which can only be seen in side view. The almost circular aperture is sur- 

 rounded by 6 articulated spines and provided with a small median tooth, broader 

 towards the tip and twice or sometimes three times cleft. The well-developed 

 ascending and generally mucronate peristome is in most cases marked off from 

 the rest of the frontal wall by a distinct line which meets the marginal furrow, 

 and the vestibular arch (figs. 1 c, Id) is continued deep into the zocecium as a 

 strongly arched lamina, with the convexity towards the basal wall of the zooe- 

 cium and its concavity towards the aperture, through which it can readily be 

 seen in zooecia boiled in caustic potash solution. Each of the lateral parts of this 

 lamina is connected with the corresponding lateral wall of the zooecium by a 

 calcareous, cylindrical rod growing out from the latter. Each zocecium is in its 

 distal half provided with 16—20 closely-placed, uniporous pore-chambers forming 

 a strongly projecting basal part, and similar pore-chambers occur in the circum- 

 ference of the kenozocecia covering the ooecia. 



The ooecia are endozooecial and the strongly arched, smooth frontal wall of 

 the covering kenozocecia sometimes shows faint, radiating striae. 



The colonies form crusts on algae, and on one of them was found a primary 

 zooecium (fig. 1 a), the aperture of which was surrounded by 12 spines. The 

 vestibular arch was in this less developed and seemed to lack the Iwo cal- 

 careous rods. 



Australia (The Botanical Museum of Copenhagen). 



