BItACIIIOrODA. 
43 
Locality .—Chorhoti Pass (1754, 1737); Bompras (C) ; 
Bimkin (ll). Fig-. 4 is a smaller variety. 
ORTHIS COMPTA. 
Plate 4, fig. 6. (1737, 1768.) 
O. xninuta, rotundo-transversa, valva dorsali convexa, profunde 
bisecta, costis 16-18 rigidis, quarum 2-3 utrinque prope sulcum media* 
num bifurcatis. Valva ventralis (?). 
A small rounded transverse species; the dorsal valve (all we 
have) convex, hut with rather a deep sharp central furrow, 
which gives it a strongly-bilobed appearance, and with eight 
or nine sharp ribs on each side, two or three of which on 
either side of the furrow are forked from about the middle of 
the shell. 
The ribs are pretty regular, about as thick as the interstices, 
and a little nodular from the crossing of the lines of growth, 
but not conspicuously so. 
The shell has a marked resemblance to the Orthis Lewisii of 
the British Wenlock rocks. 
Locality .—Chorhoti Pass (1737); Damchen (1768, 1678, 
1744). 
ORTHIS MONTICULA. 
Plate 4, fig. 7. 
O. minuta, convexa. Valva ventralis gibba, costis 22-24 subse- 
quaiibus radiata, area, magna triangulari, umbone obtusa, sinu nullo. 
Valva dorsalis (?). Long. 2 lin .; lat. 3 lin. Alt. valv. ventr. lin. 
A small species, with a very large area, of a pyramidal 
shape, and with a blunt umbo. The area is placed at a right 
angle to the general surface of the ventral valve, which is 
highly and regularly convex, without any median depression. 
It is radiated somewhat regularly by about twenty-two or 
twenty-four rod-like ribs, crossed by squamous striae of growth. 
All the ribs do not extend to the apex of the valve. They are 
