278 Report on Organic Remains. 



No. 3. Cast of one of the segments of a remarkable unde- 

 scribed Ammonite. It may be recognised by the following 

 characters. A. placenta. Orbicular. Sides diminishing 

 rapidly from the centre to the circumference, where they 

 form with each other a very acute angle. The whole exter- 

 nal and internal surfaces marked by numerous minute arbores- 

 cent sutures. Septum sinuous, smooth, except where it united 

 with the points of the shell. Here the septum is furnished 

 with robust branched tubercles, and corresponding depres- 

 sions for the reception of similar tubercles from the adjoining 

 septum. Siphunculus conspicuous, cylindrical, and funnel- 

 shaped as it approaches the septa. Placed on the margin 

 nearest the centre of the whole shell. Thickness 1*8. Pre- 

 sumed diameter G'5 



Cabinet of the Lyceum. 



PI. V. fig. 0. 



The position and size of the siphunculus will probably be 

 found to cause a distinct semi-cylindrical furrow on the ex- 

 ternal edge of the whirls. This character our imperfect spe- 

 cimen does not exhibit, and we must wait until others more 

 entire shall be discovered. The perfect shell will, doubtless, 

 be found to resemble in its general appearance, the Phonemus 

 of de Montfort, a recent microscopic shell from the Adriatic 

 and Mediterranean ; but the position of the siphunculus and 

 the smooth septum, sufficiently distinguish it from our spe- 

 cimen. Locality same as the preceding. 



No. 4. Undetermined. Probably a fragment of an Am- 

 monite. From the same locality. Imperfect as it is, it is 

 figured in order to invite the attention of our naturalists to 

 the subject. 



Cabinet of the Lyceum. 



PI. V. fig. 4. and 5. 



