[MATTHEW] NOTES ON CAMBRIAN FAUNAS, No. 12 51 
zone (d) a recurrence of darker gray, finer shales, like those of the 
sub-zone b but with the absence of lime-carrying species, and an 
absence of a tendency to form calcareous lenses. At the western end 
of the St. John basin we have found very few fossils in this sub-zone, 
(a Microdiscus occurs) elsewhere the prevailing forms are Ptycho- 
paride, especially Solenopleura and Ptychoparia. And whereas in 
the sub-zone c there are only two types of Agnostus, it is found that 
one of these types has disappeared; others have taken its place, 
especially such as have a tendency to the obscuration of the axial 
segments of the glabella, or even the entire obliteration of them on the 
surface of the head-shield. Microdiscus is also represented by its 
typical (but not oldest) form, for the earlier form, M. Dawsoni, Hartt, 
found in sub-zone b1, has disappeared. 
It has been stated on a previous page that the St. John basin of 
Cambrian rocks was protected by ridges of volcanic rocks on each side, 
extruded at the beginning of Cambrian time, but these ridges did not 
extend to the western end of the basin, where, on the northern side, 
the Basal sediments of the Cambrian were deposited on the gneisses, 
schists and limestones of a pre-Cambrian complex. 
The fauna of Hastings Cove 
At one place about four miles N.E. of St. John these older sup- 
porting rocks form a belt only a mile wide, separating the St. John 
basin from that of the Kennebecasis R. This depression is broad, 
and is now partly filled by a lake-like expansion of the waters of this 
river; here and there along this valley are detached masses of Cam- 
brian sediments, none of which show strata older than the base of the 
St. John group. Perhaps the most interesting of the patches of Cam- 
brian rocks is that of Hastings Cove a shallow indentation of the river 
just E. of Drury cove. Here a limestone hill of the pre-Cambrian 
complex rises abruptly on the S. side of the valley leaving only a nar- 
row margin of Cambrian strata at its foot. This consists of conglom- 
erate with calcareous paste containing pebbles of gneiss and limestone 
swept down from the adjoining hill of the pre-Cambrian complex; 
both in the paste of the conglomerate and in an overlying shale, are 
parts of the tests of Paradoxides abenacus, hence we conclude that these 
fossils belong to the sub-zone d of the division given on a preceding 
page, the highest sub-zone of Paradoxides known in the St. John 
basin of Cambrian rocks. But only a few of the species seen in the 
latter basin can be recognized at Hastings cove, where the fauna has 
many small species of trilobites with heavy-knobbed or tuberculated 
shields, and also forms which hitherto have been thought to charac- 
