DEVONIAN FOSSILS 99 
Ornamentation of fine costellae shows faintly on the steinkern, 
being clearer at the anterior end of the shell. The external mould 
shows the ornamentation to consist of fine costellae or striae, 
rounded in cross-section, which average 34 per em., variation 
occurring according to the frequency of new intercalations. As 
increase is by intercalation, the new fine ribs alongside the full- 
sized ones sometimes give an appearance of pairing or alternation 
of costellar size. Fine growth lines cross the costellae, with a 
frequency of the order of 17 per mm. In places there are stronger 
growth lines, generally discontinuous. In the piece of external 
mould preserved, there are also a couple of growth lines so strong 
and continuous as to form fine ridges which interrupt the 
ornament. 
Comment. The thickened shell and heavy growth lines are 
considered to be evidence of phylogerontism. Eospirifer ranges 
from Middle Silurian to Lower Devonian. Other specimens of 
Eospirifer have been figured from Victorian strata (Gill, 1942), 
and other undescribed forms are held, but the new species is 
nearest that figured in the 1942 paper on Plate VI, Fig. 8 (Nat. 
Mus. Vic., reg. no. 14,105), from Lilydale. Both have the super- 
imposed secondary folds which are well known also in E. secans 
(Barrande) whieh Shirley (1938) has figured from the Baton 
River Beds of New Zealand. However, although alike, they differ 
in the structure of the cardinalia, and the Sandy's Creek fossil 
is notably bigger. The two forms are closely related but not 
identical. 
The species is named after Mr. J. G. Easton, who collected the 
Sandy's Creek fossils. 
Genus SPIRIFER Sowerby, 1814 
Subgenus Quadrifarius Fuchs, 1923 
Spirifer (1Quadrifarius) sp. 
From locality G22 on Sandy’s Creek, there is preserved the 
steinkern of a spiriferid (specimen 27,195B). It is a ventral valve 
with a well-defined non-costate sinus on each side of which there 
are ten costae. The shell is broader than long, and the beak 
well-defined. The valve is 2-5 em. wide and 1-8 em. long, these 
measurements being taken in one plane. Dental plates 7-8 mm. 
long and about half a millimetre wide, which follow down the 
outer flanks of the costae on each side of the central sinus of the 
shell. There is also a weakly-defined median septum about 12 mm. 
long, i.e., about two-thirds the length of the shell. No external 
mould was among the fossils received, and thus it was impossible 
