138 FOSSIL FAUNA. 



PLATE TulX.— continued. 



Fig. 9. The guard of a Belemnite, eroded by some Annelide. 



Fig. 10, is a vertical section of a fragment of a Belemnite, showing the alveolus or cavity 

 for the reception of the apex of the phragmocone in the upper part. 



Fig. 11. The distal or apical part of the rostrum or guard of a Belemnite. The annexed 

 outline of a transverse section exhibits the radiated structure. 



Fig. 12. The distal part of the guard of a chalk Belemnite {Belemnitella mucronata) ; from 

 Norwich. Siliceous casts of the phragmocone of Belemnitella are occasionally met 

 with in the flints of the South Downs. This phragmocone has a longitudinal flat 

 band or ridge, extending down the dorsal aspect : the chambers are very numerous ; 

 the slit or fissure in the ventral aspect of the guard, is occupied by a thin expansion 

 of the phragmocone. 



Fig. 13. a Belemnite from the great oolite of Stonesfield {Belemnites fusiformis, of Parkinson). 

 The upper part shows the alveolus for the reception of the apex of the phragmocone. 



Fig. 14. A fragment of a guard split vertically, the flat surface showing a section of the 

 alveolus filled with spar. This specimen belongs to the Belemnites cylindriformis, 

 of Parkinson. 



Fig. 15. a Belemnite {Belemnites coniformis, of Parkinson), having part of the guard broken 

 oflf, to show the alveolus or hollow in which the apical part of the phragmocone 

 is received. The removed portion has the cast of the alveolus attached to it. 



Fig. 16, of which fig. 17, is an enlarged view, is a species of chambered foraminiferous 

 shell, called Nodosaria {N. raphanistrum, of Lamarck) ; from Sienna. See description 

 of Plate LXII. 



