HA RD WICKE S SCIENCE- G OS SIP. 



l 33 



i. A subcylindrical longer or shorter fibrous body, 

 termed the rostrum or guard ; this is the part so 

 commonly found in a fossil condition. In the front 

 or broader end of the rostrum, there is a conical 

 cavity, called the alveolus, containing — 



2. The phragmacone. This consists of a conical 

 series of chambers, with a minute globular nucleus 

 at the apex, separated from one another by curved 

 septa, perforated with apertures for the passage of 

 the siphuncle. 



The siphuncle passes through the middle of the 

 ventral wall of the phragmacone, the whole series of 

 chambers being enclosed in a thin shell wall. 



" The phragmacone is not a chambered body made 

 to fit into a conical hollow previously formed in the 

 sheath (or rostrum), as some have conjectured, but 



From the specimens which have been well 

 preserved and brought to light, much has been 

 learned with regard to the external anatomy of 

 the Belemnites. The animals are known to resemble 

 the modern cuttle-fishes, having lateral fins, with 

 eight arms, and two longer tentacles bearing suckers. 

 These suckers were provided with horny hooks. 

 The animal could also eject at will a jet of "ink, : ' 

 having an ink-sac ; the mouth was provided with 

 horny mandibles. 



This knowledge of an animal enables us to place 

 it in the scheme of classification now adopted by 

 biologists. 



Like the modern cuttle-fishes, the Belemnitidoe 

 sometimes attained a large size. It is conjectured 

 that some were four feet in length. It is probable 



mm 



W tf^-m 



1 



Fig- 73- — Restoration of an ancient Belemnite. 



Fig. 74. — Internal bones of a recent cuttle fish. 



that both sheath and cone grew together, or if any 

 difference there were, the phragmacone must have 

 been of earlier growth, and by its enlargement 

 limited the forward extension of the successively 

 deposited lacunae of the guard. The phragmacone 

 was formed on the exterior of a secretive surface, and 

 the sheath on the interior of another secretive 

 surface. The last chamber of the phragmocone is 

 very large, compared with the others" ("Mon. of 

 Belemnitidse," Phillips, Palaeont. Soc, 1865-69). 



3. The thin shell wall or "conotheca" is pro- 

 longed forwards into an anterior horny or shelly 

 plate, termed the pro-ostracum. This pro-ostracum 

 is very rarely found fossil owing to its tenuity, but 

 Huxley believes that it would, if properly preserved, 

 have afforded important generic and specific characters 

 in the classification of the Belemnites. 



also they were carnivorous. Their habits have been 

 so well described by Mr. Ansted, that I may be 

 excused quoting him. He says : " We may picture 

 to ourselves these large cephalopodous molluscs 

 reigning paramount, the tyrants of creation, enabled 

 by their rapidity of movement to chase their prey at 

 the surface, by their curious hydraulic contrivance to 

 pursue it to the depths of ocean, and by their 

 numerous arms and great strength, to conquer and 

 bring it within the grasp of their powerful jaws." 



The recent animals of this class are so fierce, that 

 even in our own seas, where they occupy a place 

 comparatively unimportant, they rank among the 

 most destructive of species in proportion to their 

 dimensions ; for if once they touch their prey it is 

 enough, neither swiftness nor strength can avail. 

 The shell of the crab and the lobster is a vain 



