7i!4 



HEMLOCK. 



intermediate between the scaly covering of the beetles 

 and the membranous wings of the flies, being semicrus- 

 taceous, not meeting together when at rest by a straight 

 suture, but having some portion of the inner margin 

 of one wing-cover folded over the other. In the order 

 thus characterised by the structure of the wings alone, 

 were included the cock-roaches (genus Blatla), pray- 

 ing mantes (G. Mantis,) and locusts and grasshoppers 

 (G. GryUtts, Linnseus), having the mouth armed with 

 jaws ; and Fulgora, Cicada, Notonecta, Nepa, Cimex, 

 Aphis, Chcrmes, Coccus, and Thrips, having (with the 

 exception of the last, which has not yet been satis- 

 factorily examined) the mouth suctorial, furnished 

 with a proboscis. Hence De Geer, by a combination 

 of structural characters, and Fabricius, following up 

 his system, derived from the cibarian organs, sepa- 

 rated the mandibulated genera from the others, to which 

 the name of Hemiptera became restricted, the others 

 acquiring the names of Ulonata, Fabr., or Orthoptera, 

 Olivier. Latreille, however, adopting a system derived 

 from general instead of isolated characters, separated 

 the Hemiptera (which Fabricius termed Rhyngota) 

 into two great sections, the first having the wing- 

 covers horizontal and of unequal consistence, tlie 

 basal portion being coriaceous, and the terminal half 

 membranous, retaining for these the name of Hete- 

 roptera, and giving that of Honwptcra to the second 

 section, in which the wing-covers are deflexed and of 

 equal consistence throughout. Moreover, in the first 

 of these divisions the rostrum, or promuscis, as it is 

 termed by Mr. Kirby, arises at the front of the under- 

 side of the head, whereas in the second it springs 

 from its posterior portion, near the base of the fore- 

 legs, and sometimes appearing pectoral. Dr. Leacli, 

 followed by Mr. Mac Leay and some other English 

 authors, considered these two groups as possessing 

 the rank of distinct orders, the first retnining the 

 name of Hemiptera, and the second Hoinoptera. 

 Kirby, also, and Latreille, from their agreement in 

 possessing an articulated proboscis, have however 

 regarded them as belonging only to one order. Mr. 

 Kirby, however, gives the following observations as 

 indicating the chief differences between them : 

 1st, " the heteropterous section usually sucks the 

 juices of animals, and the homopterous those of plants," 

 but this is by no means correct : the majority of 

 the former, as well as the latter, are plantisuges ; 

 (in the former the hemelytra, besides their different 

 substance) as well as the wings, cross each other ; 

 while in the latter the organs of flight are deflexed 

 and do not lap over each other at all. The antennae, 

 also, of the one are often long, and do not terminate in 

 a bristle ; whilst in the other,with few exceptions, they 

 are very short and setigerous. In the Heteroptera 

 the body is depressed and flat ; in the Homoptera 

 convex and thick. In the former the scutellum is one 

 of the principal features of the trunk ; in the latter 

 not at all remarkable. 



Regarding these points of distinction as of no small 

 importance in the establishment of distinct orders, we 

 find the order Hemiptera characterised by the jointed, 

 sucker-shaped mouth, the wings membranous, covered b\ r 

 wing- covers, either entirely membranous and deflexed, 

 or partly coriaceous and partly membranous and hori- 

 zontal, and the tarsi never composed of more than three 

 joints. The mouth is composed of a fleshy articulated 

 canal, terminating in a point inclosing "several fine 

 bristles, which are employed as lancets in wounding 

 the substances upon which the insects feed ; it is also 



furnished externally at the base with a small conical 

 place transversely striated, which represents the upper 

 lip of the other orders. When unemployed this pro- 

 boscis is laid along the breast, often reaching to or 

 even extending beyond the base of the hind legs ; 

 when employed it is protruded forwards. 



All the insects belonging to this order undergo a 

 series of moultings, analogous to those of other insects, 

 although less in degree. They are produced from 

 eggs as small active six-legged larvae, having nearly 

 the resemblance of the perfect insects, but entirely 

 destitute of wings or wing-covers. After shedding 

 the skin several times, gaining thereby only an in- 

 crease of size, they appear as pupae, but still active, 

 and differing only from the larvae by having the wings 

 j and wing-covers concealed in small cases placed upon 

 j the back. Another moulting brings them to the 

 j imago state, in which their wings are fully developed. 

 I In the apterous, or wingless species, the transforma- 

 j tions merely consist in a gradual increase of size at 

 I the successive moultings. The pupae of the Hemt- 

 \ ptcra take as much nourishment as the larvae. 



The majority of these insects are found in their 

 various states upon plants, the juices of which serve 

 for their nourishment ; some few however inhabit the 

 water (as the Nepidce and Notonectido;}, whilst others 

 reside upon its surface, as in Gerris, Hydrometra, &c. 

 These appear to prey upon other dead or floating 

 insects ; others fly in the air with great agility, al- 

 though they walk but slowly ; and some leap to a 

 great distance, as in the Cecrupidce. A few of the 

 species, one only of which is found in our climate, 

 attacks man, namely, the Cimex lectitlarins. The 

 majority a r e varied in their colours ; a few only (as the 

 Nepa grandis and large exotic Cicada*) attain a large 

 size ; the majority being less than an inch in length. 

 As above characterised, the order Hemiptera is 

 divisible into two sub-orders, or primary classes, the 

 Heteroptera and Homoptera, the distinctions of which 

 we have already detailed in this article. 



The sub-order Heteroptera (or the order Hemiptera 

 of Leach, Mac Leay, Stephens, &c.) is divisible into 

 two primary divisions, namely, the Geocorisa, or land- 

 bugs, and Hydrocorisa, or water-bugs. 



For the characters of the Geocorisa, see our article 

 upon that group, and that upon Cimex, in which the 

 various subsections or families are described. For 

 the characters of the Hydrocorisa, see the article upon 

 that group ; and for an account of the other sub- 

 order, and its divisions, see the article HOMOPTEKA, 

 and the various articles referred to from it. 



HEMLOCK is the Coninm maculalum of Linnaeus, 

 a common and dangerous British weed. It belongs 

 to the natural order Umbelliferce, and is nearly related 

 to the genus Smyrnium. The death of Socrates has 

 conferred such a celebrity on the hemlock, that more 

 plants have contended for the honour of bearing death 

 to the philosopher than cities for giving birth to 

 Homer. The Coneion of the ancients was a potent 

 poison administered to those condemned to death by 

 the Areopagus. Theramenes and Phocion, as well 

 as Socrates, were poisoned by it ; and although the 

 effects recorded in history are not in correspondence 

 with those we should look for from the common 

 hemlock, it is highly probable that this was the poison 

 employed. That the modern Conium is identical with 

 the Coneion of the Greeks, is rendered probable from 

 its being very common in Peloponnesus, and " most 

 abundant between Athens and Megara," according to 



