ACTINOCAMA X A C T I N O L I T E. 



placed near the vessels containing- them, at such a 

 distance as not to impart any heat, they regularly 

 closed, and did not a train expand till after the light 

 was removed. When, however, they had been plen- 

 tifully fed, they contracted more slowly, and sometimes 

 even remained open. 



The abbe, among other experiments, placed a nar- 

 row slip of meat in such a position as to enable two 

 of these animals to seize either end an animated 

 contest commenced between them to gain possession 

 of this piece, each in turn drawing in the greater 

 portion ; this lasted about three hours, at the end of 

 which, one of them having lost its hold, its antagonist 

 gained the prize. 



In Hughes's History of Barbadoes a minute account 

 is given of one species of actinia, which he considered 

 a sensitive plant, having animal properties. 



The actinia: are incapable of supporting a strong 

 light or great degree of cold ; loud sounds affect them, 

 and fresh water kills them ; when they are seen 

 expanded, they indicate fine weather with greater 

 certainty than the barometer; when left by the tide 

 for any length of time they contract themselves, 

 remaining filled with water, which they eject with 

 great violence when irritated. 



These animals, like the polypi, have prodigious 

 powers of reproduction ; they ma}' be separated trans- 

 versely or vertically, and each foliated tube becomes 

 a distinct animal ; and some time after perfectly 

 formed small actinia? issue from the mouth. 



When forcibly detached from their base, the lace- 

 rated portions, which remain attached to the rock, 

 continue to live ; their volume increases ; the form 

 swells ; its mouth, stomach, and tentacula become 

 developed, and a perfect actinia is re-produced. These 

 again produce from the latter part of their base glo- 

 bule?, buds or shoots, which are detached by them- 

 selves, and, fixing in their turn to the neighbouring 

 rocks, produce fresh colonies. 



About thirty species are known, only one of which, 

 the actinia iv'nY/w, possesses the property of stinging 

 the hand when touched, a. circumstance almost con- 

 stantly observable with the medusae. Some species 

 <jf actinia are eaten, principally in the hot climates, 

 where they are far more numerous and infinitely more 

 beautiful than in the northern latitudes. They are 

 found in all seas, lining the vaulted caverns of rocks, 

 below high water mark, or attached to the surrounding 

 masses ; and, in general, each species selects its par- 

 ticular habitat. The term Zoophyte, or animal plant, 

 has, by many naturalists, been applied to these ani- 

 mals in common with the corals, corallines, and other 

 polypidoms, equally improperly so named, as it merely 

 arises from a singular coincidence of external resem- 

 blance without being founded on any physiological 

 ath'nity. In proof of which one fact alone will be con- 

 clusive, that of their having one or many mouths, 

 leading to an alimentary cavity, or organ of diges- 

 tion, which does not exist in any vegetable. 



ACTINOCAM AX (Miller). A genus of fossil Ce- 

 phalopodous Mollusca, established by Mr. T. S. Miller, 

 who describes it to be closely related to the Belem- 

 nites. 



Generic character : " A club-shaped spathose con- 

 cretion, consisting of two nearly equal longitudinal 

 adhering portions. Apex pointed ; base, a convex 

 but obtuse cone. The whole formed of a series of 

 enveloping fibrous laminae.'' 



For a considerable time these fossils were supposed 



to be either spines of echinites or belemnites, to the 

 latter of which they have a very close affinity. From 

 the first they may very readily be distinguished by 

 their retaining their original laminated fibrous struc- 

 ture ; whereas fossil echinital spines, when broken, 

 always exhibit the uniform substance of crystalline 

 carbonate of lime, with the constant fracture of the 

 primitive rhomboid. 



From the belemnites they may at once be separated 

 by their not possessing the conical cavity or alveolus 

 for the reception of the chambered shell ; but are 

 terminated by a protruding cone similar to the spines 

 of cidarites. 



With regard to the precise situation which this 

 genus holds in the system of nature, together with many 

 others, it is only possible to reason from analogy ; and 

 the tendency of that evidence is, that it belongs to 

 the class Cephalopoda. In following out these views, 

 it appears that actinocamaxis the bone or scpiostarium 

 of an animal belonging to Lamarck's division of the 

 ccphalopodes, the sepiaria ; while the belemnites ar- 

 range among his polythalamia. 



These views, first promulgated by Mr. Miller, have 

 since received particular elucidation from the pens 

 of M. H. Ducrotay De Blainville (Memoire sur les 

 Belemnites, Paris, 1827), and P. L. Voltz (Observa- 

 tions sur les Belemnites, Paris, 1830), &c. 



This genus as yet appears to be geologically pecu- 

 liar to the chalk" formations of England and Nor- 

 mandy. 



ACTINOCRINITES (Miller). A genus of 

 fossil animals of the class Itadiata, forming a distinct 

 family, first established by Mr. Miller, under the 

 name of Crinoidea, or lily-shaped animals (particulars 

 of which family will be given under that head). 



Portions of these fossil remains have been long 

 known under the ambiguous names of wheel stones, 

 fairv stones, rosary beads, trochites, entrochites, &c. ; 

 but it is to Mr.Parkinson we are indebted for the true 

 nature of these singular and interesting remains, who 

 described a species of this genus under the name of 

 the Nave Enervate, from its resemblance to the nave 

 of a wheel. The characters of this genus are thus 

 defined : 



" Animal having a round column composed of 

 numerous joints, perforated by a round alimentary 

 canal. At the summit of the column is placed a 

 pelvis, formed of three plates, on which five first 

 costals and one irregular costal adhere, which are 

 succeeded by the second costals and intercostals and 

 scapulae ; from whence five arms proceed, forming two 

 hands, with several tentaculated fingers. Round 

 side arms proceed at unequal distances from the 

 column, which terminates at the base in a fascicular 

 bundle or root of fibres." 



The remains of this genus pervade the transition 

 and carboniferous limestone series of this country. 



ACTINOLITE. A mineral of a green colour, 

 forming an interesting variety of hornblende. It is 

 divided into Asbestos Actinolite, Common Actino- 

 lite, and Glassy Actinolite. Tiie first of these ap- 

 pears znassive, in distinct concretions, and internally 

 the lustre is remarkably brilliant. It is found in 

 gneiss, mica-slate, and granular limestone. Berzelius, 

 on exposing this mineral to the action of a blow-pipe, 

 found that it was not altered by moderate ignition ; 

 in a brighter heat it whitened, and was then converted 

 into a yellowish brown opake glass. Vauquelin thus 

 describes its chemical constitution : 



