and on Fossils in the Oxford Clay. 54-7 



The objects of the author are, first, to draw attention to the organic 

 bodies discovered in the laminated clay ; and secondly, to describe 

 the various forms which the mouth of the Ammonite assumes in 

 different species and in different stages of growth in the same 

 species. 



The fossils obtained from the laminated clay are stated to be as 

 follows : — 1. A succulent plant. 2. Lignite, with oysters sometimes 

 affixed to it. 3. Crustaceans, supposed to have inhabited the dead 

 shell of the Ammonite*. The specimen described is stated to have a 

 finely tuberculated and delicately thin covering ; the tail to have 

 the appearance of being divided into three portions, finely corrugated 

 towards their edges ; the body to have on each side internally five 

 or more processes ; and the head to be furnished with several short 

 arms and two long ones jointed a little above the head and ter- 

 minated in two claws, the longer being serrated on its inner edge. 

 4. Another allied crustacean is stated to have also an extremely thin 

 and finely tuberculated covering ; to be furnished with two long arms 

 of similar shape, each terminated at its extremity by one claw, and 

 two others projecting from about the centre ; and passing off poste- 

 riorly are two fan-like processes of similar shape. 5. Trigonellites, 

 two species. 6. One valve of a Pollicipes. 7. The remains of an 

 animal considered to have been probably allied to a Sepia. 8. Shells 

 of the genera Unio, Cyclas, Astarte, Avicula, Gervilla, Pinna, Nu- 

 cula, Rostellaria, Turritella, Ammonites f, Belemnites, and an animal 

 to which he has applied (since the paper was read) the name of Be- 

 lemnotheutis. In describing the last fossil, he states that the lower 

 part is conical, blunt at the apex, and chambered internally like the 

 alveolus of a Belemnite, with an oval siphunculus near the edge of 

 the chambers ; that it has a brown thick shelly covering which gra- 

 dually becomes thinner towards the superior part ; that immediately 

 above the chambers is an ink-bag resting on what resembles the 

 upper part of a sepiostaire, and composed of a yellow substance 

 finely striated transversely, being formed of laminae of unequal den- 

 sity ; that in some specimens, broken longitudinally through the 

 middle, are exposed long, flat, narrow processes of a different struc- 

 ture ; that immediately beneath the superior contraction are two 

 long feather-like processes, and one or more which are short, indica- 

 ting, the author thinks, probably the situation of the mouth. With 

 reference to the first part of the paper, Mr. Pearce also notices an 

 animal allied to Sepia or Loligo, one side being covered by a pen 

 resembling that of the Loligo, and having immediately underneath 

 it, at the junction of the middle with the lower third, an ink-bag 



* To this organic body Mr. Pearce has given since the paper was read 

 the name of Ammonicolax. 



\ Since the paper was written Mr. Pearce has consulted Mr. Pratt's ac- 

 count in the Annals of Natural History for November 1841, of Oxford 

 clay Ammonites, and ascertained that he possesses [A. Lonsdalii, A. Brightii], 

 \_A. Gutielmi, A. ElizabethecB], A. Comptoni, and A. Konigii. The fossils 

 included between brackets the author considers to belong to one species. 



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