47 



through the coral. The external poriferous interstices of 

 Fenestella ai-e in several species, but perhaps not in all, 

 carinatcd in the middle. 



It seems to me that there is a better mark of distinction 

 than this, at least for the Tasmanian species. In Retepora the 

 holes are at rarer intervals, and the term bars cannot be 

 applied to the tissue above or below them. It is a mass of 

 cells like the rest of the polyzoary. In Fenestella the bars 

 are sparsely celluliferous. There are calcareous points of 

 attachment to give mutual strength and support to dichoto- 

 mously dividing and spreading ligulate series of cells. The 

 transverse bars are much narrower than the celluliferous por- 

 tion, and they are given off almost at right angles, and in some 

 species only very slightly arched. It is this peculiarity which 

 causes the interstices to be more quadrangular than oval. 



Prof. Phillips thus defines the genus Qoc. cit.) : — " Greneral 

 figure spreading from a narrow base to an infundibuliform or 

 foliaceous figure ; substance, a thin stony expansion, com- 

 posed of slender radiating or longitudinal ribs variously con- 

 nected by transverse bars, so as to constitute a more or less 

 regular open network. lie adds (but the italic words marked 

 by me do not apply to all the Tasmanian species) the longitu- 

 dinal ribs margined on each side by one row of pores on the 

 outer face only." 



It must be always borne in mind that we very seldom find 

 anything but casts of these beautiful fossils. The calcareous 

 matters have been so completely dissolved away that nothing 

 remains of the old polyzoary. The casts too seldom show any 

 markings of the front or back of the cells. The most of 

 the specimens preserved by collectors are valueless as showing 

 any details. They are merely impressions of the interstices 

 or net-work markings, and nothing more. Those who are 

 very familiar with the species might determine them from this 

 alone, but it is hardly a safe identification. There are, how- 

 ever, in the Museum of this Society some specimens from 

 Maria Island, where the whole polyzoary has been beautifully 

 preserved. The calcareous matter is untouched, and the detail 

 of the cells is plainly evident. In one species, Fenestella ampla, 

 there is a raised margin round the mouth and circular depres- 

 sions, probably for avicularia. In one place also there is the 

 embossed dome of what appears to be an ovicell. Thus the 

 functions of nutrition and reproduction were in no way diffe- 

 rent from the polyzoa of the present day. It is seldom that 

 Buch an opportunity is offered for studying the details of these 

 interesting organisms. Pi-of. Phillips {loc. cit.) says " that 

 owing to the decomposition of the whole or part of the coral- 

 line substance iu argillaceous rocks these beautiful fossils 



