1896. ] NEW YORK ACADEMY OF SCIENCES. 203 
resemblance in composition and sculpture between these plates 
and the tests of trilobites some years ago, we did not then 
suspect them to be parts of Barnacles, and it was only after find- 
ing the plates of another species (S. triangularis) in intimate 
relation to the detached plates hereafter described as Cirripo- 
dites that we were led to suspect that they might be parts of 
Barnacles, and possibly such a hollow caudal plate as Dr. Clarke 
figures for Strobilepis. If we admit this, however, we must also 
be prepared to allow that while this caudal plate was of caleareo- 
chitinous composition the lateral plates of the same creature 
were thicker and calcareous. 
Another possible explanation of these little plates is that they 
correspond to the dorsal row of small conical plates such as is 
scen on Strobilepis, but this seems less likely on account of 
their comparative thinness and flexibility. 
Among the fossils of the St. John group which the author in 
previous papers has assigned to Stenotheca there are two types, 
that just described and another chiefly characteristic of a lower 
horizon. It is true that all these minute fossils have certain 
characters in common, as the compressed conical form, the 
strong ribbing of the surface and the thickened dorsal band. 
But they have also points of difference, for in the forms de- 
scribed below the ribs (except in one) do not increase in number 
on the dorsal side; they are more distant from each other, and 
there are pores or perforations at their extremities; these pores 
or holes form a row along the dorsal ridge and sometimes also 
along the ventral. 
The acquisition of better examples of Stenotheca triangu- 
laris than were in hand when this form was described, has led 
the writer to conclude that there are important differences be- 
tween it (and some others described with it) and the typical 
Stenothecze, enough to constitute specific, if not generic differ- 
ences between them, if they were complete organisms; but as 
they are possibly only parts of organisms it is unnecessary to 
make any generic distinction until the general structure is known. 
In the first examples studied it was not observed that the sur- 
face visible was not the outer surface of the test, but the surface 
of the mould of the interior, and the “long cylindrical apex ” 
described and figured is really an internal tube in the apex of 
the cone. 
STENOTHECA TRIANGULARIS. (Plate XIV., figs. 4a and 40.) 
Stenotheca triangularis, Trans. Roy. Soc. Can., vol. ili., pt. 
iv., p. 58, pl. vi., figs. 5 and 5a. 
Stenotheca triangularis, Trans. Roy. Soe. Can., vol. viii., 
pt. iv., pp. 133, 154. 
