123 
Locality and formation—Not uncommon in the Hamilton Formation, Bartlett’s Mills, 
near Arkona, Township of Bosanquet. 
CRUSTACEA. 
The remains of Crustacea are not uncommon in both the Corniferous Limestone and the 
Hamilton Formation of Western Ontario ; but they are for the most part ill-preserved and 
fragmentary, and I have only been able to identify with certainty the well known species, 
Proetus crassimarginatus (Hall), Phacops rana (Green), Dalmanites Boothii (Green), and Le- 
perditia (?) punctulifera (Hall). Besides these, our collection includes fragments of some five 
or six additional species of Trilobites, which must be retained for further examination, 
153. PRoETUS CRASSIMARGINATUS (Hall). 
Calymene crassimarginatus (Hall), Geol. Rep. Fourth Dist. New York, p. 172, fig. 5. 
Phillipsia (2) crassimarginatus ; eited by Billings, Can. Journal, Vol. VI. p. 362. 
Proetus crassimarginatus (Hall). Fifteenth Report on the State Cabinet, p. 100. 
This familiar species is chiefly known by its pygidium, which is a common fossil in the 
Corniferous Limestone. The pygidium is somewhat wider than long, very convex, and mar- 
-gined by a thick concentrically-striated border, whence the specific name is derived. The 
axis is strongly convex and prominent, with thirteen or fourteen rings ; and the lateral lobes 
are also very convex, and exhibit from twelve to thirteen ribs (Fig. 56). Along with the tails, 
occur sometimes exceedingly convex and prominent glabelle and also free cheeks, both of 
which probably belong to this species. 
Locality and Formation.—Corniferous Limestone, Ridgeway, Port Colborne, Lot 6, Con. 
1 Wainfleet, and Hagersville. 
154. DALMANITES Booruit (Green). 
Crypheus Boothii (Green), Silliman’s Am. Jour. of Science, Vol. 32, p. 344. 
Crypheus calliteles (Green), Ibid., p. 346. 
Dalmanites Boothii (Hall), Fifteenth Report on the State Cabinet, p. 91. 
The tail of this pretty little species (fig..56c.), which is commonly known by the name 
of Dalmanites calliteles, is a by no means very rare fossil in the Hamilton Formation of Onta- 
rio. The pygidium is semicircular, with a moderately prominent, tapering axis, which, when 
complete, exhibits from nine to twelve rings. The lateral lobes are depressed, and exhibit 
five or six pleurx, the extremities of which are prolonged beyond the margin in the form of 
so many obtusely-pointed processes or expansions which are gently curved backwards. 
Between the lateral groups of these processes, occupying the centre of the pygidium is a 
wider and shorter pointed process extending backwards from the rounded extremity of the 
axis. The entire surface is ornamented with minute papille or granules. 
Locality and Formation—Hamilton group, Widder, and Bartlett's Mills, near Arkona, 
Township of Bosanquet. 
155, PHacops RANA (Green). 
Calymene bufo, var rana (Green), Monograph, p. 42. 
Phacops rana (Hall), Fifteenth Report on the State Cabinet, p. 93. 
This well-known species is chiefly represented by detached heads, though the pygidium 
is not of very uncommon occurrence, and the body-rings are occasionally seen. The cephalic 
shield (fig. 56a.) is nearly semicircular, and the posterior angles are slightly produced back- 
wards, The glabella is very gibbous, but somewhat depressed on the upper surface; about 
one-third wider than long; the lobes obscurely marked out; the neck-furrow narrow but well- 
defined ; and the neck-segment wide and conspicuous. The eyes are large and prominent, 
rising nearly as high as the top of the glabella, with large lenses. The thorax is one-third 
longer than the head, its sides nearly straight, and its axis about as wide as the lateral lobes, 
or nearly so. The pygidium is twice as wide as long, or wider, regularly rounded behind, 
