Potsdam of Wisconsin and Lake Superior. [231] 7 
prominent, with its posterior portion inarticulate and broadly 
rounded. There is no limiting farrow separating it from the 
lateral lobes; and posteriorly it fades insensibly into the ter¬ 
minal border. The lateral lobes are but faintly articulate, and, 
meeting behind the axis, form a border three-fourths of an inch 
broad, whch is strongly curved downward on all sides, and 
presents a ciircularly curved outline, without any indications of 
caudal appendages. 
The foregoing was written before seeing Prof. Hall's memoir; 
and I had referred the specimens to Dicellocephalus ) with a query. 
I could scarcely doubt of their generic distinctness, but felt re¬ 
luctant to engage in genus-making without ampler materials. I 
am happy now to recognize Prof. Hall’s new genus as exactly 
meeting my want. This species differs from P. Miniscaensis Hall, 
in its broader and fuller movable cheek and broader margin, 
and much longer genal points. 
II. The University has for many years been in.possession of 
some fucoidal remains from the red sandstone of the south 
shore of Lake Superior. As it is so uncertain when any further 
paleontological data will be obtained from that region, I do not 
deem it necessary to defer longer a brief notice of these fossil 
Algae. 
There are two methods of frond-arrangement noticeable among 
these remains. One exhibits a rudimentary symmetry, while 
the other is totally destitute of it. There is little difficulty in 
deciding that neither form falls under any description that has 
been published ; but it is nearly or quite impossible to determine 
whether these differences are of generic, specific, or still inferior 
value. The great variation exhibited in the arrangement of the 
different portions of the fronds of recent marine algae, shows how 
little dependence can be placed upon descriptions founded on 
detached fragments of these fossil fucoids. Those differences 
which have been sometimes recognized as marking the bounds 
between distinct genera, may easily have co-existed upon the 
same frond. There was great plausibility in the method pur¬ 
sued by the older writers in referring all these remains to the 
single genus Fucoides. 
There seems, nevertheless, some prospect of utility in making 
such distinctions as we are able; and while I cannot vouch for 
the generic characters of the fossils under consideration, I shall 
refer them provisionally to a Paleozoic genus established by 
Prof. Hall to receive some fucoids from the Calciferous sand- 
rock of New York. 
Pal^eophycus articulatus, n. sp. 
Consisting of large, straight or geniculated, compressed-cylin¬ 
drical, irregularly articulated, branching stems. The largest 
