JBtrttouarj? of gmmatrlr 



and inanimate objects, that it would be 

 difficult indeed for the moat patient na- 

 turalist to describe them. Myriads swarm 

 around us : they float in our drink ; over- 

 spread our food and fruits ; and if viewed 

 with a microscopic eye, would make some 

 loathe the choicest viands, and nauseate the 

 most delicious productions of nature. The 

 Mites possess great powers of life, resisting 

 for a time the application of boiling water, 

 and living long in alcohol. It is a species of 

 Acams that Mr. Crpsse is thought to have 

 produced by galvanic action ; but naturalists 

 who have attended closely to such matters 

 can readily and rationally account for their 

 production in the usual way. 



ACASTA. A genus of Cirrhipedes, found 

 imbedded in sponges. [See BALANUS.] 



ACCENTOR. A group of Passerine birds, 

 many of which are peculiar to America ; 

 but including also our well-known Hedge- 

 sparrow (Accentor modularis). 



ACCIPITRES. The first order of birds 

 in the Linnacan system, comprising such as 

 have the beak or upper mandible hooked, 

 and an angular projection on each side near 

 the point ; as the Eagles, Falcons, Hawks, 

 and Owls. They are among birds what the 

 Carnivora are among quadrupeds. 



ACEPHALAE. An order of Mollusca, 

 distinguished by having no apparent head, 

 but a mouth only, concealed in the bottom, 

 or between the folds, of their mantle. The 

 testaceous Acephalse are by far the most 

 numerous ; all Bivalve shells, and some 

 kinds of Multivalves belonging to them. 

 [See LAMELLIBKANCHIATA ; and for a fa- 

 miliar example, see OYSTER.] 



ACERA. A name applied to a group of 

 Apterous insects, characterized by the ab- 

 sence of antennas. 



ACERJ3. A family of Gasteropodous 

 Mollusca, distinguished by the tentacula 

 being so much shortened, widened, and se- 

 parated, that there seem to be none at all, 

 or rather, they form together a large, fleshy, 



' and nearly square buckler, tinder which the 



I eyes are placed. They approximate in many 

 respects to the Aplysice. The shell, in those 



j which have one, is more or less convolute, 

 without a visible spire, and the mouth has 

 neither sinus nor canal. The genus Bulla 



I belongs to this family. 



ACHATINA. A genus of terrestrial 

 Pneumonobranchous Gasteropods, popularly 

 known by the name of agate-snails. They 

 are characterized by an oval oblong shell, 



! striated longitudinally, with the aperture 



j ovate, and never thickened or reflected, and 

 a smooth, straight columella, truncated at 

 the base. All the species are oviparous ; and 

 among them are some which are the largest 

 of all land shells. They always live near 



; water about trees, and are very plentiful in 

 Africa, near the Cape of Good Hope. Some 

 are found in the West Indies ; an-1 there 



, are two small species, Achatina acicala and 

 Achatina octona, found in England, among 



I the roots of trees at the base of limestone 



rocks. The Achatina cohtmnaris is one of 

 the most remarkable of land sheila ; it is 

 reversed, and the columella forms a winding 

 pillar, visible within, quite to the summit 

 of the spire. Many are covered with a thick 

 epidermis, as the Achatina zebra ; but others 

 are destitute. 



ACHATINELLA. A small genus of 

 shells, differing from Achatina, in having 

 the inner edge of the outer lip thickened, 

 and a slight groove near the buture of the 

 spire. 



ACHERONTIA. A genus of Lepidop- 

 terous insects belonging to the family Sphin- 

 ffidce. Of this genus there are two or three 

 species closely resembling each other : one 

 of these is found in this country ; and is 

 known as the DEATH'S-HEAD HAWK-MOTH 

 (Acherontia atropos). This magnificent in- 

 sect varies in the expanse of its wings from 

 four to considerably more than five inches. 

 The upper pair are of a very dark brown 

 colour, varied with black, especially near the 

 base, near which is an undulated bar of pale 

 ochre : the disc is varied with deep black 



BEATH'8-HEAD HAWK-MOTH 

 (AOHKROHTIA ATROPOS.) 



undulated lines, and ferruginous patches, 

 minutely irrorated with white, of which 

 colour there is a central spot, and several 

 wavy connected bars beyond the middle. 

 The posterior wings are fulvous orange, with 

 a narrow central and a broader dentated bar 

 running parallel with the hinder margin. 

 The head and thorax are brownish black, 

 the latter with a large pale, skull-like mark 

 on the back : the abdomen is fulvous, with 

 the incisures of the segments black, and a 

 lead-coloured stripe runs down the back. 

 When disturbed or irritated, this insect emits 

 a squeaking sound. From this circumstance, 

 as well as from the singular mark just 

 mentioned, its appearance is regarded with 

 much dread by the vulgar in several parts 



B 2 



