(19) 
both on fracture, P.4, fig. 8. pl. 2, fig. 7 : it does not appear, however, that he thought 
of making a longitudinal section of the Echinus, such as M. Beudant has submitted, pl. 
1, fig. 8. pl. 2, fig.8. A Belemnite, in the collection of the Conseil des Mines, which has 
not entirely passed into the calcareous state, presents in some of its parts the same 
spongy and radiated tissue which we observe in the spines of the Echinus. This Belem- 
nite also offers the peculiarity of a nipple at the base, with projecting sides, striated 
transversely, and ee ole from the centre to the circumference ; the centre is per- 
forated by a small shallow round hole: the summit sometimes terminates in folds. 
Pl. 4, fig. 10,141,412. Some present a large conical cavity at the base, which has been 
often considered as the last chamber or dwelling of the animal; others have none, 
or at least a very small cavity. Theophrastus’s description of the lynx stone is not 
applicable to the Belemnite : it would seem that we owe the first notice of it to 
Pliny, but it is not quite clear whether his dactylus deus (1. 37, c. 10) which he 
clearly distinguishes from the lynx stone (1. 8, c. 38) was a fossil species of Echinus 
or Belemnite. In the 15th century they were considered to be meteoric stones, and 
marvellous medicinal virtues were ascribed to them. Boetius de Boot, in his 
Treatise on Stones, pronounces them to be petrified darts, and it was not until the 
end of the 16th century that they were first regarded as natural organised bodies. 
Erhart, in 1724, appears to have been the first who concluded them to be shells 
akin to the Nautilus. Deluc insisted that the Belemnite was an organised bone, 
like that of the Sepia; and they have been concluded by other authors to be sta- 
lactites; petrified wood; the teeth or the back bones of fish; the tusks of the 
Narwal ; Crocodile’s teeth ; tubulites, etc. ete. Cuvier, Régne Animal, t. 2. p. 371. 
Sage, Jour. de Phys. ventose, an. x. Beudant, Observations sur les Belemnites. 
Ann. du Mus, t. 16. p.77. Faure Biguet. Considerations sur les Belemnites, etc. Lyon, 
4819. 
Orthoceratites. 
Mr. Farey ‘‘ finds them referable to twenty different places in the British series 
of strata; extending from (4st) the London clay above the chalk, to (20th) the lime- 
stone resting on slate.” According to Spallanzani, the islands of the coasts of Dal- 
matia are masses of orthoceratites. M. Sage thinks, from the sections he has made, 
pl. 4, fig. 24, that the Orthoceratites are alveoli of different species of Belemnites, and 
contained within the funnel, pl. 4, fig. 29, which, however, according to M. Beu- 
dant, does not always exist. This opinion has not been generally adopted. Deluc, in 
particular, combated it (Journ. de Phys. vent. an. 12.), asserting that the alveoli 
of the Belemnites have no siphon. M. Sage considers the organization of the 
siphon to be evident in pl. 4, fig. 27, and in the centre of fig. 25, which is confirmed 
by Platt and Beudant : Montfort seems to have viewed the alveoli as the envelope 
of a parasite. Breynius submits fig. 30 as an orthoceratite, with the siphon passing 
through the axis; fig. 35, as the convex front of the last articulation, with the 
siphon, of a species found most frequently in the marble of Oeland, on the coast of 
Sweden, four feet long, and only two inches in diameter at the base; fig. 34, or 
the same part of another species, whose diameter is three inches, whence he infers 
its length to be more than five feet; fig. 11, p.2, isthat of a species from Gothland 
with a large siphon at the circumference, and remarkable for the projecting rays, 
sometimes filled with crystals of fluor, the proportion between the length and the 
diameter appeared to be 10:1. Dissertatio Physica de Polythalmiis. Gedani, 1732. 
Some are smooth, others have circular sides ; both kinds are found in the greyish 
marble of Norway 5 they are of a whitish calcareous spar, with a case or envelope 
of a reddish brown ; the chambers are separated by hemispherical yellowish lines. 
Hippurites. 
Some consider what we call the operculum to be the last septum, in which case 
the shell may be interior, unless it is hereafter discovered to be a bivalve: fig. 26, 
pl. 1, shows the gutter or canal, c. which replaces the siphon ; fig. 28 is the under 
part of a convex operculum, with two prolongations having the appearance of a 
