(7) _Oxalate of lime calculi_ (_mulberry calculi_) (Pl. XI, fig. 2).-- These are characterized by their extremely rough, angular surface, formed by the octahedral crystals of oxalate of lime. Their specific gravity may be 3.441, and they contain oxalate of lime to the extent of 81 per cent, together with carbonates of lime and magnesia and organic matter. (8) _Gravel_ (_pultaceous deposits_).--Simple crystals may be met with at any point from the kidneys to the external opening at the end of the prepuce (sheath), and they may appear singly, as crystals, or they may accumulate in masses of fine spherical crystals almost like dirty powdered chalk suspended in water. In the ox this is especially common as a collection in the sheath, distending that into a soft, doughy swelling. FORMS OF CALCULI IN DIFFERENT SITUATIONS. Apart from the rough crystalline surfaces of the calculi of oxalate of lime and ammonio-magnesium phosphate, the general tendency is to a smooth, round outline. At times, however, they show more or less flattening with rounded angular edges, caused by the contact and mutual friction of two calculi. Sometimes two or more stones lying together become united into one by a new external deposit, and the resulting mass then shows rounded swellings on opposite sides. The large calculi occupying the pelvis of the kidneys usually show a central part having the outline of the main cavity of the pelvis and two or more projections that have been molded into the corresponding branches or channels which lead to corresponding lobes of the kidney. In winter and spring small concretions in the form of plates are often met with in the branches of the pelvis, having been formed and molded in the confined space between the projecting papilla and the surrounding cuplike branch of the pelvis. Finally, the pulplike deposits in the sheath and elsewhere are made up of globular masses, individually so small as to be often practically microscopic. STONE IN THE KIDNEY (RENAL CALCULI). [Pl. XI, fig. 1.]