GREEN OR CHLORITE SAND. 73 



6. My tilus. Casts of a small species, with acuminated beaks, the anterior 

 side truncated and slightly curved ; a few concentric markings, probably 

 the hnes of growth, are perceptible. 



7. Modiola imbricata? Min. Conch, tab. 212. figs. 1, 3. The form 

 of the casts so closely corresponds with that of the figures referred to, that 

 1 have but httle hesitation in considering them as the remains of the 

 same species, although the imbricated external surface has not been 

 noticed in the Parham specimens. 



8. TelUna. The casts of a small flat species ; these are very numerous. 



9. CucuUea. A few excellent casts in which the transverse teeth of 

 the hinge (the characteristic mark of this genus) are very distinctly shewn; 

 the impression of the external surface has not been observed. Some of 

 the specimens are of the size and form of C. decussata (Min. Conch, tab. 

 206. figs. 3 and 4.), and in all probabihty belong to that species ; an 

 impression of the markings of the interval between the beaks, resembles 

 those of C. oblongata, (Min. Conch, tab. 206. figs. 1 and 2.) 



10. Trigonia clavellata. Min. Conch, tab. 87. The casts of this 

 species are from three to four inches long, and exhibit the structure of 

 the hinge and the situation of the muscular impression. The markings 

 of the external surface, upon which its specific characters depend, are also 

 beautifully preserved. 



11. Trigonia aliformis. Min. Conch, tab. 215. The casts of this 

 species are very bold and sharp, and seldom exceed an inch in width ; the 

 impressions of the external surface are not uncommon. 



12. Venus. The casts of a shell of this genus are very numerous ; 

 it is an inch long, the width a httle exceeding the length ; the external 

 impressions have not been observed. 



IS. Crassatella? The cast of a species allied to this genus. 



14. Yenexiczxdiva, planicosta9 Min. Conch, tab. 50. Several remark- 

 ably perfect casts of a venericardia, aUied to this species, have been 

 obtained from the more compact masses of the ironstone ; they differ 

 however from V. planicosta in their width exceeding their length, and in 

 having but one muscular impression, which is placed near the posterior 



