A FOSSIL ISOPOD OF THE FRESHWATER GENUS PHREATOICUS. 367 



Downs-Walloon Coal Series in Southern Queensland. This position 

 for the St. Peter's fossil beds places the horizon in the Jurassic 

 and above the fossil bed at Ipswich, which is probably Upper 

 Triassic." (1916, p. 10.) 



Further information is given by Mr. Tillyard in his paper 

 under the " Summary of St. Peter's Results" (1916, p. 43). 



In forwarding the specimens Mr. Tillyard writes on May 

 31st, 1917:— 



11 The beds are usually classed as Trias-Jura, but evidence is 

 accumulating that will probably place them in the Upper Trias, 

 probably as the nearest Australian equivalent of the Rhsetic." 



The species of Phreatoicus is represented in the speci- 

 mens sent to me by about ten impressions. Of these Mr. 

 Tillyard writes (June 5th, 1917):— 



"Most of the Crustacea appear to have been found in the actual 

 < Nodules' of the 'False Coal' band formation, from which the 

 Fish, the Unios, and most of the insects were also derived. Some, 

 however, come from the paler unaltered shales with plane fracture- 

 surfaces. All the specimens are much carbonised, so you will have 

 to rely solely on outline drawings to illustrate the fossils." In 

 addition to the specimens sent to me there are, Mr. Tillyard says, 

 4i a large number of less satisfactory specimens as well, some being 

 on large hand-specimens of rock of considerable weight." 



All the specimens are the property of Mr. B. Dunstan, 

 Chief Government Geologist of Queensland. 



Of the specimens described below, the first three are from 

 impressions on dark coloured rock, the remainder are from 

 the paler unaltered shales. 



I proceed to describe these impressions in detail, starting 

 with the most complete, i.e., in the order in which I first 

 examined them. The measurements given were made 

 direct from the specimens without reference to specimens 

 of the existing species, comparison with which was not 

 made till after I had examined all the fossil specimens. 



