CEPHALOPODA. 15 



In others, the ORTHOCERATITES*, it is altogether straight. It is 

 not improbable that the animals belonging to these shells, resem- 

 bled that of Nautilus or of the Spirula. The 



BELEMNITES 



Probably belong also to this family, but it is impossible to ascertain 

 tin- taut, as they are only found among fossils ; every thing, however, 

 proves them to have been internal shells ; thin and double, that is, 

 eomposed of two cones united at the base, the inner one much shorter 

 than the other, and divided into chambers by parallel septa, which are 

 concave on the side next to the base. A siphon extends from the 

 summit of tin external cone to that of the internal one, and continues 

 tlu nee, sometimes along the margin of the septa and sometimes 

 tlm-ugh their centre. The interval between the two testaceous cones 

 is filled with a solid substance, in some composed of radiating fibres, 

 and in others, of self-involving conical layers, the base of each being 

 on the margin of one of the septa of the inner cone. Sometimes we 

 only iiud this solid portion, and at another we also find the nuclei of 

 the chambers of the inner cone, or what are termed the honeycomb 

 cells. Most commonly these nuclei and the chambers themselves 

 i ive left no other traces than some projecting circles on the inside of 

 the internal cone. In other specimens again we find 'more or fewer 

 of the iiiu-lei. and still in piles, but detached from the double conical 

 sheath that enveloped them. 



Of all fossils the Belemnites are the most abundant, particularly in 

 chalk and compact limestone. f 



M. de Blainville divides them according to the greater or less depth 

 to which the internal cone or chambered portion penetrates, or as the 

 rdgos of the external cone have a small fissure or not, or as the exter- 

 nal surface is marked on one side by a longitudinal furrow, or by two 

 or more furrows towards the summit, or finally as that surface is 

 smooth and without furrows. 



Bodies very similar to Belemnites, but without a cavity and with 

 a rather prominent base, form the genus actinocamax of Miller.(a) It 



Breyn. de Polythal., pi. Hi, iv, v, and vi. ; and Walch, Petrif. of Knorr., Snpp. 

 IV, b, iv, d, iv. See also Sage, Journ. de Phys. an. IX, pi. i, under the name of 

 uite. 



t The best works on tbis singular genus of Fossils, are the Memoires sur Its 

 Belemnites considerees zoologiquement el g&oloyiquemtnt , by M. de Blainville, Paris, 



0^7* fa) Mr. Miller gives the following description of the genus Actinocamax 

 which he has established and separated from the Belemnites. 



Gen. Char. A club-shaped Spathose concretion, consisting of two nearly equal, 

 idiiuil adhering portions. Apex pointed: base a convex, but obtuse cone. 

 Thr \\hole formrdof a series of enveloping fibrous laminae. 



Specific character. Act. verus. A club-shaped Spathose semi-transparent horn 

 (olomol ronrrctinn ; base convex, obtuse, conical; apex submamillar. Sides de- 

 pressed towards the lower end, showing two longitudinal, towards the apex branch- 

 ing, impressions of blood vessels. 



The species was found in the Chalk Strata in Kent, Wiltshire, and Sussex, in the 

 strata which contain marine animals, so that Mr. Miller does not hesitate to consider 

 it as an inhabitant of the sea. ENG. ED. 



