171 



9. Scaphites. A multilocular shell, commencing with 

 spiral turns, the last of which, after being enlarged and 

 elongated, is contracted and reflected. Fossil. PL vi. 

 fig. 6. 



10. Spirula. A multilocular shell, partly spiral and 

 partly straight: the whirls circular, separate from each 

 other, and the last elongated in a straight line; the 

 septa plain, concave outwards, and pierced, nearly at the 

 margin, with a shelly siphuncle. Recent and fossil. 

 PL vi. fig. 7. 



11. Lituites. A multilocular shell, partly spiral and 

 partly straight ; the whirls circular and contiguous, but the 

 last elongated in a straight line ; the septa transverse, con- 

 cave outwards, and pierced, nearly at their outer margin, 

 with a siphuncle. Fossil. 



The figure of the preceding genus will suffice for this, 

 only with the conceived difference of the whirls being con- 

 tiguous, and a greater length of the straight part. The 

 student should be guarded in his conclusions with respect 

 to the contiguity of the whirls in these fossils. The contact 

 is, necessarily, only in a line passing horizontally through 

 the middle of the spiral ; and as these fossils are constantly 

 imbedded, this line of contact can only be seen when the 

 artist is so successful as to make his section exactly in this 

 line : if the section is made the least beside the central, 

 widest, part of the tube, the whirls will not be seen in con- 

 tact, but will appear separate, in proportion as the section is 

 distant from the centre. 



12. Hamites. A multilocular hook-formed shell, with 

 sinuous septa, pierced with a marginal siphuncle. Fossil. 

 PL vi. fig. 8. 



13. Orthoceratites. A multilocular straight, or slightly 

 bent, cylindrical, or slightly conical shell ; the chambers 

 separated by plain septa, concave towards the larger end, 

 and pierced with a siphuncle. Fossil. PL vi. fig. 9. 



