ZOOLOGY. 553 
tance from the apex of each side to the middle of the opposite 
face being .25 inch, .375 inch and .46 inch. The calculi are, in 
appearance, not unlike the common clay stones of the Connecticut 
River Valley though darker in color. They are composed of a 
series of concentric Jayers, which are quite a dark brown at the 
centre, but of lighter shades towards the outside, so that the 
color and appearance of the fractured surface is quite like the well 
known “ Gibraltar Rock.” The layers do not seem to differ in 
any other respect than depth of color. They are of somewhat 
variable thickness but for the most part they are from .01 inch 
to .03 inch and are much more distinct near the exterior than at the 
centre, where it is with difficulty that they are seen. The surface 
of all is smooth and polished and of a greenish brown color. 
The fracture is uneven and glassy. A chemical analysis of sev- 
eral by Mr Collier showed their composition to be somewhat pecu- 
liar, as they were found to be a triple phosphate of ammonia and 
Magnesia with a little water and traces of lime and uric acid. 
All that were broken contained some foreign substance as a 
nucleus. In two instances this nucleus was a carpet tack, in the 
others a bit of stone. The specific gravity is 1.724 and the 
hardness somewhat less than calcite and rather more than selenite. 
The horse from which these objects were taken was sixteen years 
old and was sick only twenty-four hours before it died and, until 
the calculi were discovered, was supposed to have Bots. I am 
unable to find any mention of calculi as occurring in either stom- 
ach or intestines but I am told that similar ones to those described 
have been found in the stomach of the sheep in more than one in- 
Stance, and Prof. Collier has handed me a fragment of one, which 
he Says came from the stomach of a cow which when freshly broken 
has precisely the same appearance as those just described from the 
and is of nearly the same specific gravity, being 1.7049. Tf 
the mass, of which this piece is a fragment, was a perfect sphere, 
it must have been eighteen or nineteen inches in circumference. 
The following table gives the dimensions and weight of ten of 
of the calculi :— 
name daei Wet. eee de Wa 
inches inches grains, inches inches grains 
2.94 2.94 5.625 No: 6. 62 43 40 
96 68 160 uF, 60 Ad 30 
93 66 140 i 8 51 32 23 
68 5T 55 “ 9 46 - 
63 40 43 * 10. .46 25 15 
