138 



CLASS INS EC TA. 



ORDER C OLEOPTERA. SHEATH-WINGED. 



|>art of the body, not prominent ; shell sessile, fixed, orbiculate, convexo- 

 conical, four-valved ; valves unequal, united ; sutures distinct ; operculum 

 internal, bivalve. 



This genus was established by Dr. Leach, and, excepting Pyrgama, is the 

 only one of the Balarddii with bivalve operculum. Type, C. Verruca. 



Illustration : Creusia spinulosa. 



ACASTA. A small genus formed by Leach from Balanus, but which 

 Sowerby has again reunited. They are found imbedded in sponges, have 

 a subconical shell which consists of eight unequal valves ; base cup-shaped 

 (an accidental character according to Sowerby) ; no internal plate ; shelly 

 part foliaceous. See also Balanus. 



Illustration : Acasta Montagui. 



BALAITUS. Body sessile, inclosed in an operculated shell ; arms nume- 

 rous, in two rows, unequal, articulated, ciliated, each composed of two 

 cirrhi placed on a peduncle, and capable of being exserted beyond the oper- 

 culum ; mouth not prominent, having four toothed transverse jaws, besides 

 four hairy palpiform appendages. Shell sessile, fixed, univalve, conical, 

 truncated at the apex, closed at the base with an adherent testaceous lamella. 

 Aperture somewhat triangular or elliptical : operculum internal, composed 

 of four valves, which are moveable, and inserted near the internal base of 

 the shell. 



The shell of the Bdani is immoveable in all its parts ; it forms a cone, 

 generally more or less short and truncated, fixed, without any intermediate 



peduncle, on marine bodies. It appears to be univalve, but is in fact 

 composed of six different portions, exclusive of the base, which are united 

 by a very exact suture, and are, as it were, soldered inseparably 

 together in old shells, especially in some of the larger species. 

 The animal would l>e exjwsiid to numerous injuries, were 

 it not for the operculum, which consists of four moveable 

 pieces, allowing the animal to protrude its cirrhi at pleasure. 

 The general form of the operculum is a short cone. The 

 manner in which the Balani increase their shells is not understood. 

 The species are very numerous, of which several are natives of our coast. 

 Lamarck enumerates nearly thirty, and there are probably many more un- 

 discovered, as well as others not yet properly distinguished. They are 

 found adhering to rocks, corals, shells, &c., and are frequently brought at 

 the bottoms of ships from different parts of the world ; in which situation 

 many very interesting species have been discovered. 



Illustration : Balanus tintinabulum. 



CONIA. Shell quadripartite, divisions equal ; operculum bipartite. 



Type : Balanus porosus. 



Illustration : Coma mdgaris. 



CLISIA. Shell fourpartite ; valves of the operculum undivided. 



Some species inhabit the coast of Great Britain, being found attached to 

 marine plants, Crustacea, and testaceous mollusca. 



Illustration : Clisia verruca. 



CLASS VI. INSECT A. 



AKTICTJLATED ANIMALS WITH AETICULATED FEET. 



INSECTS form a very important Class among Articulate Animals. They are characterised by the division of their body into three principal 

 parts, the head, chest, and belly, caput, thorax, abdomen ; which are less determinately marked in some Insects, as in the Beetles, 

 than in the Wasps, in which the chest is connected by one pedicle in front with the head, and by another behind with the belly. 

 They are also furnished with three pairs of legs, and generally with two pairs of wings, all which are attached to the chest. No 

 Insect, however, is thus perfectly formed when first bursting from the egg, in which its animal existence commences, but passes 

 through two stages, during which it, in most instances, differs remarkably from the form which becomes its own in the third stage. 

 These changes are called the Metamorphoses of Insects, and are said to be Complete or Incomplete as the animal assumes a more 

 or less perfectly distinct form in its several stages : a familiar instance of the first kind is presented in the Silkworm, its chrysalis 

 or grub, and its moth or perfect grub, and its moth or perfect form ; of the second, the Common Cockroach, in which the animal 

 proceeds through its primary stages of nearly the same form throughout, except that it does not obtain wings till it acquires its 

 perfect form. The three stages of Perfect Metamorphoses are, 1. The Larva, Caterpillar or Maggot ; 2. The Pupa, or Chrysalis, 

 which is remarkable on account of the animal becoming perfectly quiescent and ceasing to feed ; but during this state, a most 

 wonderful change is going on within its external covering, which leads to the production of 3. The Imago, or Perfect Insect. In 

 the Imperfect Metamorphoses, the larval stage is indicated by the absence of scutellum and wings in the Winged Insects ; the 

 second stage has been named by Lamarck the Nympha, and is distinguished in Winged Insects by the rudimental appearance of 

 wings, which are fully developed only in their perfect state. There is only space here to observe further, in reference to the 

 imperfect state of Insects, that the body consists of a series of rings, usually thirteen ; that some are headless, and that others have 

 heads, as the Maggot of the House-fly, and the Caterpillars of the Butterflies ; that some have not any feet, as the Maggot, and 

 that others have feet, some on the three rings immediately following the head, as in Cetonia Aurata, such being specially called 

 Larvae; and some, besides these, six horny legs, having membranous appendages called prolegs, on the ventral and anal segments. 

 as in the Silk Moth ; to such the name Caterpillars, ErucoK, is particularly attached. 



ARRANGEMENT OF THE PLATES. 



Plates I. and II. contain examples of the several orders as found in 

 Lamarck's arrangement; and the three succeeding Plates exhibit a more 

 extended and general classification. Definitions of orders in the first 

 arrangement are not repeated in the second. 



LAMARCK'S ARRANGEMENT OF INSECTS. 

 ORDER I. COLEOPTERA. SHEATH-WINGED. 



THIS class of insects include all those whose wings are covered by coria- 

 ceous elytra, or wing-covers. 



ILLUSTRATIVE EXAMPLES. 

 I'LATE 1. 



LUCANUS. No apparent lip ; languet divided into two long, silky 1- 

 chin covering, by its length, the larger part of the jaws. 



Type of the genus is the common Stag Beetle, also our 



Illustration : Lucanus cervus, found in groves and amongst trees in th. 

 summer evenings. 



LAMPYUIS. Thorax half circular, entirely hiding the head; mouth very 

 small ; maxillary palpi ending in a pointed joint ; the hinder extremity of 

 the abdomen phosphorescent, and the eyes large, especially in the males. 



