342 



MOLLU^CyV. 



ylmmoJif/cs, Lam., is restricted to the species in w]i\r] 



fissure ; from the exterior surface being marked with a longitudiiial gutter on one side, or with two or 

 several gutters towards the summit ; or as tliat surface is smooth and witliout gutters. 



Some fossils, very much like the Beleninites, hut witlioiit a cavity, ami even with a [)rotrLidiiig basis, 

 form the genus Actinocamaw of Miller. 



It is U|i0!i similar conjectures lliat the classification of tlie 



Ammonites, Brug., or Snake-stonep, — 

 Is founded, for they, also, are only found iu a fossil state. They are distingLushcd, in general, from 

 Nautilus, by their septa, which, ijistead of being plain or simply concave, are angulated, sometimes 



undulated, but oftener gashed on the margins, 

 like the leaves of the Acanthus. The smallness 

 of I heir last cell leads to the belief that, like the 

 Spirula, tlicy were internal shells. The beds of 

 the secondary mountains swarm with tiiem,and 

 we find tlicm thne from the si/.e of a hean 

 to tliat of a eliariiit wlircl. The variations 

 of their w liorls and of llieir s\phnn enable 

 them to lie subih\ ided. Tims the name 

 the wliurls arc vi^_i!)!c. Tlieir syphon 

 is near the margin. Tliey have been still further dii^tingnished into tlio^e which have the margins 

 of the septa fuliaccous, (the Ammoiiifes, the Plaiiitcs of Ilaan,) and into those in which they 

 are simply angular and undulatory (the Ceratites of Ilaan). Those in which the last whorl envelopes 

 all the others, arc the OrhuMles, Lam., or the Glohifes ami ConiafiJea of Ilaan, or Pehr/uses, i\lontf. 

 The i-y|ih(in is the same as in Ammonites.* The name Scaphifps, Sowcrby, [orraiher of Parkinson,] 

 has lieen ;>p])ro]niated to those species whose whorls are contiguous and on the same plane, excepting 

 tl;e h^st, which is detached and hent up')n itself. Those which are perfectly straight are the BactdUes, 

 Lam. Some arc round, others are compressed ; ami in the latter we some- 

 tinui'S observi; the syphon to be laterah The Ilamilcs of S(j^vcl■b}■, [Par- 

 kinson.] arc kno^\n by liaving their first formed cells arenatcil. Buit the 

 Titrrilile^, Mmiif., ditlVr more than anyfrom iheuMinl iiahit of the family, 

 for the wliijrls, in [)lace of remaining on the same level, descend rapidly, 

 aud give to the shell that obelisk form which is denominated turriculated. Fi^'. is^.— lortinn ,.f aBnuiite 



From analogy, it is supposed that we ought to refer to the Cephaln}n.)ds, and to consider as being in- 

 ternal shells 



The Camerixep, Crug. (Xaniii/i'li/r.';, Lam.), — 

 For all of them are equally fossil. They lia\c a lenticuhir shape, without any apparent aperture, but 

 within there is a spiral cavity, divided by se^ita into a multitude of hltle chamljers without a syphon. 

 Tlicyarc amongst the most generally diffused fossils, and almost of themselves form some entire chains 

 of calcareous hills, and immense banks of building stone. (It is upon such rocks that the pyramids of 

 Egypt are founded, and with stones of the same description that they are built.) 



The commonest, and which attains the largest size, are altogether discoid, and have only a sin^de 

 row of chambers in the whorl of the spire. Some minute sorts of this description have been also found 

 recent in some seas. Other minute species, both hving and fossil, have their margin bristled with jiolnts, 

 wliieh give to th in the figure of stars {Su'lrrortlhi.'s, Lam.). 



The woiks; and the jjatieut researches undertaken successively by LHanclii {c-x .hoius P/ancifs), Soldani, 

 riehtel and iMoll, and Alex. d'Orbign}", lia\c made known an astnnishing nundier of these chandicred 

 and esyphonal shells {Nin>innihiy'ni:), of exti'enie litllcness, so as iifteii lo be altogether microscopical, 

 either in the sea, among sand, sea-weed, lVc. ; or, in a fossil state, in the sand-lx'ds of various countries ; 

 and these shells vary to a remarkable extent in their contour, the number and the lelalive position of 

 their chambers, &e. One or two species, the only ones in whieh the animals have been noticed, have, 

 apparently, a small oblong body surniounted by numerous rcy\ tentacula, a structure which, taken in 



