486 Whitney's Description and Analysis of 
a well marked valve between this and the spirals ; the spiral 
portion, cut open, 2 inches wide at the top; at the bottom, 
3 inches; walls three lines thick at middle part, gradually 
becoming thinner at each end; 34 spirals, covered with a fine 
net-work, injected less and less as you descend. Half an 
inch from anus, an oval pouch, 1 inch long, half an inch wide. 
Rectum, cut open, 3 inches wide, very thin. 
The ducts of the liver, spleen and pancreas opened into the 
spiral portion. 
This fish should take a lower rank in the class of sharks, 
from the shape of its tail. 
ART. XXXVII.—DESCRIPTION AND ANALYSIS OF THREE MIN- 
ERALS FROM LAKE SUPERIOR. By J. D. WuirNEY. 
I. WOLLASTONITE OR TABLE-SPAR. 
'Tur Wollastonite which is found on Lake Superior differs 
considerably in external characters from any known variety of 
that mineral. Indeed, its true nature could only be recog- 
nized by chemical examination. It is remarkable for. its 
excessive toughness, which quality it seems to possess ma 
higher degree than any known mineral. It is compact, with 
an uneven fracture. Its color is light flesh-red ; hardness, 6; 
Ifistre vitreous to pearly. It is readily decomposed: by acids, 
the silica separating in the form of a flocky precipitate. 
The analysis of two specimens gave the following results: 
L Osxdidin: II. 
Silica 49.09 25.51 49.06 
Lime 46.38 13.18 44.81 
Protox. of manganese 48 | ps 
Alumina 23 1.28 
Magnesia 14 2.96 
ater 2.96 90. 
