DIBEANCHIATA. Ill 



and Solenhofen. They are usually the " gladius " or rudi- 

 mental shell. Some of these are slender, like the pens of the 

 recent Ommastrephes, and, as in them, furnished with a small 

 conical appendix (Plesioteuthis) ; whilst others are broad, and 

 pointed at each end (Beloteuthis). The most common form 

 has the shaft wide and longer than the wings ; it has a nac- 

 reous lining, and is usually accompanied by a large and well- 

 preserved ink-bag (GeotevJhis, fig. 34, 4). These were called 

 Belemnosepia by Agassiz and Buckland, who supposed them 

 to belong to the same animal with the Belemnite. In Lepto- 

 teuthis Myr. the hinder end of the gladius is truncate. In 

 Celamo it is produced into a slender stem, supporting a broad 

 oval plate. One species (Mastigophora hrevipinnis*), with a 

 broad and flat gladius, appears to have had the eight ordi- 

 nary arms produced each into a filamentary appendage. 



Similar instances of the preserved soft parts of an extinct 

 family of Dibranchiates (Belemnitidce) are of frequent occurrence 

 in the Oxford clay near Chippenham, which retains not only the 

 horny (chitinous) pen and ink-bag, but also the muscular mantle, 

 the rhombic terminal fins, and at least the bases of the arms 

 with their minute hooks, and traces of the mandibles. Horny 

 claws, like those of the uncinated Calamary (Onychotcuthis), 

 have been observed arranged in double series in the lias of 

 Watchett, and they sometimes occur in great numbers in the 

 coprolitic remains of the Iclithyosaur. The most remarkable 

 examples of this kind are preserved in the lithographic lime- 

 stones of Solenhofen, and shew that the extinct Calamary 

 had ten nearly equal arms, the tentacles, in their retracted 

 condition, being unclistinguishable from the rest — each fur- 

 nished with 20 to 30 pairs of formidable hooks. What further 

 evidence was needed respecting the nature of this creature 

 has been supplied by the Chippenham fossils, which in all 



* Catalogue of Fossil Invertebrata in the Museum of the College of 

 Surgeons, London. 4to, 1856, p. 1. 



