THE JURASSIC SYSTEM. ^3 
Among these beds the limestone is by far the most important ; it is 
found on the left bank of a small stream at an old ruin known as 
Mekyigiinru, near Lungma "droksa,"^ eight miles to the south of 
Kampa dzong (PI. g, fig, 2). 
The total thickness of the band is only about 50 feet, but the 
rock is hiuhly fossiliferous, and, considering its 
Lungma limestone. . . . 
proximity to the granite of Chomoyumo, the 
fossils are wonderfully well preserved. They include lamellibranchs, 
brachiopods, cephalopods and gastropods, and are of great interest 
and value as furnishing a definite horizon in the Jurassic system. 
They have not yet been worked out in detail, but the following list 
includes the leading genera and a few characteristic species : 
Cephalopoda. 
Harpoceras [Dorsetensia) cf. complanatum Buckman. 
„ several other species. 
Stepheoceras cf. humphresianum Sow. 
Nautilus sp. 
Belemnites sp. 
Brachiopoda. 
Rhynchonella quadriplicata Ziet. 
„ variabilis Schloth. 
„ other species. 
Terebratula cf. ventricosa Ziet. 
Lamellibranchiata. 
Trigonia costata Park. 
„ sp. 
Pecten sp. 
Pholodomya sp. 
? Lima peciiniformis Schloth. 
Ostrea sp. 
Pleuromya {Myacites) cf. adjectus Phil). 
' " Droksa " = summer grazing-groupd. 
' These will probably be found to include other genera, such as Sonninta 
Buckman, 
