INK-BAG. 283; 



The fact of these animals having been provided with so 

 large a reservoir of ink, affords an d. priori probability that 

 they had no external shell; the ink-bag, as far as we yet 

 know, being a provision confined to naked Cephalopods, 

 which have not that protection from an external shelly 

 which is afforded by the shell of the N. Pompilius to its 

 inhabitant, that has no ink-bag. No ink, or ink-bags have 

 been ever seen within the shell of any fossil Nautilus or 

 Ammonite : had such a substance existed in the body of the 

 animals that occupied their outer chamber, some traces of 

 it must have remained in those- beds of lias at Lyme Regis, 

 which are loaded with Nautili and Ammonites, and have 

 preserved the ink of naked Cephalopods in so perfect a con- 

 dition. The young Sepia officinalis, whilst included within 

 the transparent egg, exhibits its ink-bag distended with ink, 

 provided beforehand for use as soon as it is excluded ; and 

 this ink-bag is surrounded by a covering of brilliant nacre- 



nitc from the inferior Oolite near Nortliampton, in which one lialf of the 

 fibrous cup being- removed, the structure of the conical shell of the alveolus 

 is seen impressed on a cast of iron-stone, and exhibits undulating' lines of 

 growth, lilie those on the exterior of the shell of N. Pompilius. 



M. Blainville, although he had not seen a specimen of Belemnite in which 

 the anterior horny conical chamber is preserved, has argued from the ana- 

 logy of other cognate chambered shells that such an appendage was apper- 

 tinent to this shell. The soundness of his reasoning is confirmed by the 

 discovery of the specimen before us, containing this part in the form and 

 place which he had predicted. "Par analogic elle etait done evidemment 

 dorsalc et terminate, et lorsqu'elle 6t;iit complete c'estil dire pourvue d'une 

 cavile, I'extremite postericure des visceres de I'animal (tres-probablement 

 I'organe secreteur de la generation ct partie du foie) y etait renfermee." — 

 Blainville Mem. sur les Belemnites. 1827. Page 28. 



Count Munster (Mem, Geol. par. A. Boue, 1832, V. 1, PI. 4, Figs. 1, 2, 3, 

 15,) has published figures of very perfect Belemnites from Solenhofen, in 

 some of which the interior horny sheath is preserved, to a distance equal to 

 the length of the solid calcareous portion of the Belemnite (PI. 44', Figs. 

 10, 11, 12, 13,) but in neither of these are there any traces of an ink-bag. 



