282 ANIMAL BELEMNO-SEPIA. 



The transverse plates are outwardly concave, inwardly con- 

 vex ; and are perforated by a continuous siphuncle, (PI. 44, 

 Fig. 17, b.,) placed on the inferior, or ventral margin. 



We have already (Ch. XV. Section II.) described the 

 horny pens and ink-bags of the Loligo, found in the Lias at 

 Lyme Regis. Similar ink-bags have recently been found 

 in connexion with Belemnites in the same Lias. Some of 

 these ink-bags are nearly a foot in length, and shov/ that the 

 Beleniho-sepicE,* from which they were derived, attained 

 great size. 



* In 1829, I communicated to the Geological Society of London a notice 

 respecting the probable connexion of Belemnites with certain fossil ink- 

 bags, surrounded by brilliant nacre, found in the Lias at Lyme Regis.. (See 

 Phil. Mag. N. S. 1821), p. 388.) At the same time I caused to be prepared 

 the drawings of fossils, engraved in PI. 44", which induced me to con- 

 sider these ink-bags as derived from Cephalopods connected with Belem- 

 nites. I then withheld their publication, in the hope of discovering certain 

 demonstration, in some specimen that shoiild present these ink-bags in 

 connexion with the sheath or body of a Belemnite, and this demonstration 

 has at length been furnished by a discovery made by Professor Agassiz 

 (October, 1834,) in the cabinet of MissPhilpotts, at Lyme Regis, of two im- 

 portant specimens which appear to be decisive of the question. (See PI. 

 44', Figs. 7, 9.) 



Each of these specimens contains an ink-bag within the anterior portion 

 of the sheath of a perfect Belemnite ; and we are henceforth enabled with 

 certainty to refer all species of Belemnites to a family in the class of Cepha- 

 lopods, for which I would, in concurrence with M. Agassiz propose the name 

 01 Bele?nno-sepia, Such ink-bags are occasionally found in contact with 

 traces of isolated alveoli of Belemnites: they are more frequently surrounded 

 only by a thin plate of brilliant nacre. 



The specimen (PI. 44"', Fig. 1,) was procured by me from Miss Mary 

 Anning in 1829, who considered it as appertaining to a Belemnite, Near 

 its lower end we see the lines of growth of the horny anterior sheath, 

 but no traces of the posterior calcareous sheath ; within this horny sheath 

 is placed the ink-bag. The conical form of this anterior chamber seems 

 to have been altered by pressure. It is composed of a thin laminated 

 substance (see PI. 44", Fig. 1, d.,) which in some parts is brilliantly 

 nacreous, whilst in other parts it presents simply the appearance of horn. 

 The outer surface of this cup is marked transversely with gentle undula- 

 tions, which probably indicate stages of growth. Miss Baker has a Belem- 



