THE BELEMNITE. 



171 



illustrative examples of the Belemnite have since been obtained; and 

 in a supplementary paper read before the Koyal Society, February 14th, 

 of the present year (1850), I have stated what appears to me to be the 

 extent of our present knowledge of the organization of the Belemnite. 

 I subjoin an abstract of that paper, which embodies the result of an 

 examination of many hundred specimens of Belemnites and Belemnoteu- 

 thites. The annexed outline, or diagram, shows the known structures 

 of the Belemnite ; of the soft parts of the animal, a few imperfect car- 

 bonaceous traces, apparently of the mantle, around and between the 

 shelly processes of the upper part of the phragmocone, are the only 

 vestiges I have been able to detect. The most perfect Belemnite hitherto 

 discovered consists of, 



1. An external Capsule (e) which invested the osselet or sepiostaire, 

 and extending upwards, constituted the external sheath of the receptacle. 



2. The Osselet, characterized by its fibrous radiated structure, ter- 

 minating distaUy in a solid rostrum or guard («'), having an alveolus, or 

 conical hollow (^), to receive the apical portion of the chambered 

 phragmocone, and expanding proximally into a thin cup, which became 

 confluent with the capsule, and formed the receptacle (b, b,) for the 

 viscera. 



3. The Phragmocone (d), or chambered, siphunculated (c), internal 

 shell; the apex of which occupied the alveolus (^) of the guard, and 

 the upper part constituted a capacious chamber, from the basilar margin 

 of which proceeded two long, flat, testaceous, processes (a, a,). 



These structures comprise all that are at present known of the 

 animal to which the fossil commonly called " Belemnite,'" belonged. 



Of the Belemnoteuthis, the cephalopod which Professor Owen 

 considers to be a Belemnite, many examples of the body with eight 

 uncinated arms and a pair of long tentacula, and with an ink-bag, and 

 palleal fins, have been discovered. The osselet of this animal, like that 

 of the Belemnite, has a fibro-radiated structure, investing a conical 

 chambered shell; but this organ, for reasons fully detailed in the memoir, 

 could never have been contained within the alveolus of a Belemnite. 



No certain evidence has been obtained of the occurrence of an 

 ink-bap in natural connexion with a Belemnite. 



In the annexed outline the several parts are represented in their 

 natural relative positions. The capside, or most external investment, (e) 

 is seen only in section, being removed to expose the rostrum or guard 

 (the fossil body generally known as the Belemnite). The upper three- 

 fourths of the rostrum are also taken away, to show the phragmocone 

 which it originally enveloped. The straight transverse lines denote the 



Diagram op the known Struotdkes of the Belemnites- Puzosiamis, fkosi Tkowbbieoe. 



a, a, doisal processes. /, the inferior end of the phragmocone. 



b, b, the receptacle. g, the alveolus of the guard. 



c, c, the siphuncle. A, vertical section of the guard. 



d, d, the phragmocone. z, the guard, or rostrum of the osselet. 



e, the capsule. k, sulcus, or furrow, on the ventral aspect of this species of Belemnite. 



/, capsule, or periostricum. 

 m, the dorsal line. 



», transverse section, showing the fibrous 

 radiated structure of the guard. 



