ZONE OF HARPOCERAS SERPENTINUM. 



125 



species of the Harpoceras genus are comparatively rare. Belemnites compressus, 

 Gresslya donaciformis, Area truncata, and Biscina reflexa, are also abundant. 



2. The Commune-Beds are found at a little distance above the Serpentinum-heAs ; they 

 are crowded with small specimens of Steph. commune, Steph. annulatmn, Belemnites 

 irregularis, Astarte striatosulcata . 



3. The Serpentinum-Beds lie below the preceding, and consist of clays and layers of 

 nodules of limestone, of much coarser texture than those of the " Fish and Insect Beds." 

 Harpoceras serpentinum , Harp, falciferum, Harp. Lytheyise, Harp, elegans, and Harp, 

 radians, are found in abundance with some Belemnites and other shells. 



Professor Judd gives several sections of the Upper Lias, two of which I will quote as 

 examples of the petrology of the series. On the left bank of the stream at Hallaton 

 Perns the junction of the Middle with the Upper Lias is well seen in a number of drain- 

 fields. The succession of the beds here is as follows : 



Upper Lias 



Middle Lias 



1. Dark blue clays. 



2. Ferruginous beds, with Harpoceras serpentinum (abundant) and Harpoceras bifrons. 



3. Paper-sliales, with fish and insect limestone and usual fossils. 



4. Sandy, ferruginous band, with nooulds of shells. Marlstone rock-bed. 



5. Light-coloured clays, with ironstone balls. 



Upper Lias : 



Serpentinum 



BED 



Prom a railway cutting near Market Harborough we have the following section 



1. Soil. I foot. 



2. Boulder clay. 2 to 3 feet. 



3. Upper Lias clay, with Stephanoceras commune and Belemnites compressus. 

 It consists of laminated blue clay, weathering to a yellow colour. 1 to 

 4 feet seen in the pit. 



4. Hard, brown, ferruginous hand of impure ironstone. 9 in. 



5. Softer and more sandy bed, completely full of Harpoceras serpentinum, 

 Harp, bifrons, Stephanoceras commune, Steph. Holandrei, Belemnitet 



I compressus, and other shells. 9 in. 



I. 6. Hard, very ferruginous bed. 3 ft. 6 in. 

 r 7. Light-blue, laminated clays. 3 ft. 4 in. 



8. A thin vein of sandstone, very inconstant. 1 ft. 



9. Light-blue laminated clays. 5 ft. 



10. Marlstone rock -bed of the Middle Lias. Amaltheus margaritatus, Bel. paxillosus, 

 Cardium truncatum, Avicula novemcostce, 



11. Brown clay. 2 to 3 feet. 



^ 12. "Skerry," with nodules containing Cardium truncatum, Avicula ojgnipes, 

 Lima sp. 



13. Brown clay. 2 to (! feet. 



14. Blue clay. 7 to 9 feet. 



15. "Skerry" (brown sandstone). 1 to 6 feet. 



16. Brown clay. 2 to 3 feet. 



17. Rock, water-bearing stratum, further sinking prevented. 



Middle Lias : 



Margaritatus 



BED 



