Mr EtheTidge on Fossils from Bowen River Coalfield. 279 



P. ampla (Lonsdale), the type of the genus Protoretepora, but 

 with this exception, that the entire habit of the polyzoarium 

 is on a smaller scale. Whether to consider this as a variety 

 only of P. ampla, or as a distinct form I am at a loss to 

 decide, a state of uncertainty which is not diminished by the 

 regular gradation traceable through a series of specimens pre- 

 viously referred to, as in the British Museum Collection. 

 Careful measurements of the number of fenestrules in the 

 space of an inch vertical on the surface of these examples 

 shows that, from the typical P. ampla, where there are pretty 

 constantly 9 or 10, we pass through such gradations as poly- 

 zoaria with 14 or 15, another with 16 or 17, and an extreme 

 of 18 to 20, and this it must be borne in mind without any 

 material change in the other features, beyond such as would 

 of course be caused by increased or decreased growth. I 

 have investigated this matter somewhat fully in company 

 with my colleague, Dr "Woodward, F.E.S., who agrees with 

 me as to the difficulties attending specific separation amongst 

 these Australian Polyzoa. Of course it is just possible that, 

 had we the perfect fronds to deal with, matters might be 

 simplified, but as they are at present only known to me as 

 casts, little more can be said just now. 



The non-celluliferous face of the present Queensland speci- 

 mens is minutely striated, the fenestrules are oval and of 

 medium size. The cellules are arranged in quincunx, and 

 in from three to six oblique rows on the interstitial surface, 

 but more commonly the rows are four. 



Loc. and Horizon. — Identical with the preceding species 

 (Nos. 64, 81, 93, 109, etc.). 



Genus Fenestella — Miller and Lonsdale, 1839. 



(Murchison's "Silurian System," p. 677.) 

 Fenestella^ sp. ind. 



(Compare F. fossula (Lonsdale), in Strzelecki's "Phys, Descrip. N. S. Wales," 

 1845, p. 269, t. 9, f. 1 and la.) 



Ohs. — This is a dense probably infundibuliform species, in 

 which the number of rows of cells on the interstices varies 

 from two to five, the increase taking place a short distance 



