REPOET ON THE POLYZOA. 
77 
natural state the entire area is filled in by a rather thick epithecal membrane, in which 
alone is seated the semicircular or subcrescentic operculum. Fertile cells distinguished 
bv their greater width. 
This curious type appears to have been first noticed by Mr. Macgillivray, who 
describes the zoarium in his specimens as “ small, foliaceous, and convoluted,” and Mr. 
Hincks as “ foliaceous and bilaminar or incrusting.” The few fragmentary specimens in 
the Challenger collection, on the other hand, represent portions of a small zoarium, 
composed of narrow, compressed ligulate branches, dividing irregularly in a furcate 
manner. The zooecial character, however, in the main corresponds so exactly with that 
given to Caleschara denticuiata by Mr. Macgillivray and Mr. Hincks, as apparently to 
reduce the Challenger form to a mere variety of that species. 
With respect to the systematic position of Caleschara, opinions may well be divided, 
its characters at different stages of growth passing from those of a simple Membranipora, 
through Amphiblestrum to Micropora, with which latter genus it is very closely allied, 
differing in fact almost solely in the absence of a complete calcareous border round the 
mature oral orifice. On the whole, and taking the characters from the fully matured 
condition, I am disposed to agree with Mr. Macgillivray in thinking it worthy at any rate 
of subgeneric rank. 
Caleschara denticuiata ?, var. tenuis (PL XXI. fig. 9). 
Character — Zoarium erect, composed of narrow, ligulate, compressed, bilaminar 
branches. Frontal areas pyriform, separated by very wide, bevelled ridges, and 
deeply depressed in the middle, where an elliptical aperture is left, occupied in the lower 
two-thirds by a thick calcareous lamina attached below to the lower border of the aperture, 
and on each side above to its sides, leaving on either side an elongated fissure. The 
edges of the lamina toothed, and its surface, as well as that of the interzooecial ridges, 
strongly granulated. 
Habitat — Station 162, off East Moncoeur Island, Bass Strait, 38 fathoms, sand and 
shells. 
[Var. foliacea and Crustacea, Queenscliff and Victoria, Mr. Watts ; Curtis Island, 
Bass Strait, Captain Warren.] 
Family XII. Electpjnida:. 
Eledrinidce, d’Orb., 1851, Palaeont. Eranr., p. 329. 
Memh'amjioridce (pars), Auctt. 
Character — Zoarium erect or incrusting, more or less flexible or subtestaceous. 
Zooecia turbinate or subturbinate. Wall punctured. A wide expanding aperture, the 
