46 
VICTORIA MEMORIAL MUSEUM. BULLETIN NO. I 
The following are the principal measurements of the type: — 
Length, 190 mm.; width, 120 mm.; width axial lobe of thorax, 
50mm.: length cephalon, 94mm.; width, 120 mm.: eyes, 
length, 12 mm.; back of eye, 17 mm. from posterior margin of 
cephalon; distance between eyes, 50 mm.: pygidium, 70 mm. 
long; 115 mm. wide. 
This species is readily distinguished from I. gigas by its 
broader and more rounded form, and its shorter and wider 
cephalon and pygidium. Local collectors in Ottawa have called 
this form Asaphus platycephalus , to distinguish it from the more 
triangular Isotelus gigas. The inadequate figures of Stokes 7 
species, which was never described, prevent its positive identi- 
fication, and the name will have to be dropped. The Museum 
of the Geological Survey contains a number of specimens of 
Isotelus from St. Joseph island, but none of the size of the one 
described by Stokes. The specimens which we have are all 
Isotelus gigas , and the presumption is that Stokes' specimens were 
of that species also. Even with the types, the point could hardly 
be definitely decided, so, as just remarked, it is much better 
to drop Stokes' name. 
Locality. — This species is rather common at Ottawa in the 
cherty layers of the Crinoid zone, and less so in the Prasopora 
and Cystid zones of the Trenton. The exact locality from which 
the type was obtained is not known. On the tablet in the 
Museum it is marked “Trenton, Ottawa, Ont., J. McMullen, 
collector.” The Museum number is 1788. 
Isotelus maximus, Locke. 
Plate IV, fig. 8. 
Isotelus maximus, Locke, 1838. Second An nual Report 
Geological Survey of Ohio, p, 246, figs. 8, 9. 
Isotelus megistos , Locke, 1841. Transactions American Asso- 
ciation of Geologists and Naturalists, p. 221, PL 6. 
Isotelus and Asaphus megistos of authors. 
A small specimen of this species collected from the Lorraine 
at Hawthorne, near Ottawa, Ont., by the writer, is figured, to 
show the great length of the genal spines in a young specimen 
of this species. 
