254 Canadian Record of Science. 
In the later of the two Acadian species of Protolenus 
(P. paradoxoides) there is a narrowing of the fixed cheek 
and prolonging of the glabella (as compared with the 
earlier species, P. elegans), which, carried further, would. 
give rise to a trilobite similar in the form of the head to O. 
(?) Forresti. It appears to the writer therefore that this 
species should also be included in Protolenus. 
Ellipsocephalus. 
As already remarked no species of this genus has hither- 
to been satisfactorily shown to exist in America, and it is 
necessary to look to the Old World for species which may 
be compared with those existing in Eastern Canada. 
In the Holmia Kjerulfi beds of Sweden are two trilobites 
which have many points of resemblance to the two LEllipo- 
cephali described in this article. It is true that one of 
these species is referred to Arionellus, but it possesses an 
extended eyelobe and in other respects does not fully accord 
with that genus; the points of departure are all in the 
direction of Ellipsocephalus, and thus it appears to cor- 
respond with H#. articephalus, only it has a much wider 
glabella. 
Similarly the other species is a counterpart in many 
respects of H. galeatus only the Swedish form has not so 
wide a front margin, nor the cylindrical glabella, bell shaped 
in front, of a typical Ellipsocephalus. Still these two 
trilobites not inadequately pee esent the,two Ellipsocephali 
described above. 
It may be mentioned in this connection that Mr. Walcott 
has described a new genus of Cambrian trilobites under the 
name of Avalonia, which by the form of the glabella and 
fixed cheek is allied to Ellipsocephalus, if indeed it be not a 
sub-genus of that group.’ It will be observed that the 
species EH. articephalus has a furrow across the shield in 
i 1 Ae RE Paradoxides lagren, Stockholm, 1883, p. 20, tab. iv. figs. 1, 
and 
2 The eyelobes on the figure appear to have been introduced by the artist, as 
they are not mentioned in the description of the genus. 
