ICHYOSARCOL I TES IGUANA. 



a mass of sixty eggs of some lepidopterous insect 

 found upon the osier, and brought to De Geer, not 

 one had escaped the Ichneumon. But it is chiefly in 

 destroying the larvse of other insects that the Ichncu- 

 monidee are serviceable, although a few instances are 

 recorded in which the eggs are not deposited until 

 the victim has arrived at the pupa, or even the perfect 

 state. Of those which destroy the larvae, the majority 

 are internal feeders, but a few have been observed 

 which remain on the outside of the caterpillar until 

 it dies ; of this kind are the larvse of a large orange 

 coloured species, Ophion luteum, which feed on the 

 caterpillar of the pussmoth (Centra vinula). We have 

 already given instances of the attacks of these para- 

 sites upon hymenopterous, dipterous, and homopterous 

 insects, in the cases of the wild bees, wheat-midge, 

 and the plant lice. Other species of these orders are 

 similarly infested with Ichneiimonidte as well as the 

 Coleoptera, but the great mass of the species belong- 

 ing to the family are appropriated to the order Lepi- 

 doptera, which they destroy in all their states, and in 

 every situation, whether naked and exposed like the 

 caterpillar of the cabbage butterfly, or buried in the 

 whorls of a leaf like the Tortrices, or hidden in the 

 substance of a leaf as the mining Tineee. 



But, as if to show the endless convolutions of the 

 great chain of nature, these parasites are themselves 

 subject to the attacks of other and smaller parasites 

 belonging to the same family. Of these, various 

 instances have been well authenticated ; and it is 

 remarkable with what admirable precision of instinct 

 these second parasites must acquire the knowledge 

 that particular caterpillars are already attacked by 

 the insects which are to furnish their own progeny 

 with support. 



Latreille has divided this family into three princi- 

 pal groups, from the number of joints in the palpi ; a 



character which is, however, not strictly to be relied 

 upon in certain species. 



The first ?roup comprises those species in which 

 the maxillary palpi are five-jointed and the labial 

 four-jointed, and the first submarginal cell is united 

 with the discoidal cell, and the second submarginal 

 cell is very minute, being either rounded or square, 

 although sometimes it is entirely wanting. This group 

 comprises the Ichneitmonidce of Stephens, a family of 

 such great extent that Gravenhorst has published a 

 description of the European species alone, occupying 

 nearly three thousand octavo pages. Here belong 

 the genera Pimpla, having the ovipositor very long ; 

 Cii/ptus, Ophion, having the abdomen sickle-shaped ; 

 Banchus, Hcllwigia, Joppa, Ichneumon, having the 

 ovipositor not exserted ; the abdomen, narrowed, and 

 the base and the head transverse ; Afomyia, Peltastes, 

 and others. Mr. Stephens has described 2123 species 

 of the restricted genus Ichneumon, in the seventh 

 volume of his Illustrations. 



The second group comprises those species which 

 have the maxillary palpi five-jointed and the labial 

 four-jointed, and consists of the family or sub-family 

 which we have already described under the name of 

 BRACONIU.T:, which see. 



The third group comprises those species which 

 have the maxillary palpi six-jointed and the labial 

 four-jointed, and comprises the Alysudce of Stephens, 

 comprising the genera Alysia, Chelomis, Sigalphus, 

 and others. 



ICHYOSARCOLITES. A fossil genus of shells, 

 of which only one species is known ; in general ap- 



823 



pearance it may be said to resemble the Nautili, Litu- 

 ola, and Spirula genera ; but it has peculiarly distinct 

 characteristics, and merits the honour of constitu- 

 ting a genus. 



ICICA (Aublet). A genus of South American 

 trees belonging to Decandrue, and to the order Tere- 

 binthaceee. Generic character : calyx four-cleft per- 

 sisting ; petals broad at the base, "seated below the 

 germen ; spreading stamens inserted into the bottom 

 of the calyx, under a circular disk ; filaments shorter 

 than the corolla ; anthers oval, erect, and two-celled ; 

 style short ; stigma two-headed ; drupe two-valved ; 

 nut double. The fruit of one of these trees is very 

 fragrant, and used as a perfume. The wood of I. al- 

 tissima is very durable, and used for making house- 

 hold furniture, boats, &c.: as stove plants they succeed 

 with the ordinary management. 



IGUANA. A genus of saurian reptile, and the 

 one which is perhaps most generally characteristic of 

 those animals which are known by the general name 

 of lizards, though Cuvier makes it the name of his 

 third family, Sauria. The iguana?, properly so called 

 form the second section of the family, and are distin- 

 guished from the first family by having teeth on the 

 palate. The general characters are : the body and 

 the tail covered with small imbricated scales ; a range 

 or crest along the back, consisting of spines, or of 

 scales, which are erected, compressed, and pointed ; 

 under the throat there is an appendage of skin, form- 

 ing a sort of ruff in that part, the edges of which are 

 supported by a cartilaginous production of the 

 os hyoides ; their thighs have a range of tuber- 

 cles, like those on the true lizards ; each jaw is fur- 

 nished with one row of teeth, which are compressed, 

 triangular, and trenchant ; and there are besides two 

 rows of small teeth on the posterior margin of the 

 palar.t There are several species, and as is the case 



throughout almost the whole class of reptiles, there is 

 not a little confusion about t'he history of at least 

 some of them. Those which strictly belong to the 

 genus are, we believe, all inhabitants of the American 

 continent, and chiefly of the tropical part of it, though 

 some are found, at least, as far north as the southern 

 parts of the United States. 



COMMON IGUANA (7. lulerculata). This species 

 is found in tropical America, especially in Guiana, 

 and the countries westward to the shores of the Pa- 

 cific ; it grows to a large size, being in general three 

 feet long, and specimens measuring five feet are not 

 rare. The shape of the animal is not considered very 

 handsome, in consequence of the prejudice which 

 exists against the whole race of saurian reptiles, 

 which are all very harmless creatures, with the excep- 

 tion of the larger ones which inhabit the waters ; the 

 upper part is greenish yellow, marbled with pure 

 green, and having the tail anulated with brown ; but 

 the colours are variable, according to the position of 

 the light, and the state of excitement in the animal, 

 being blue, violet, green, and even black ; the under 

 part is of the same colour with the upper, but much 

 paler ; there is a crest of large spiny scales all down 

 the back ; a large plate on each side of the head, at 

 the angle of the jaws ; the sides of the neck are 

 covered with pyramidal scales more thinly set than 

 the rest ; and the margin of the enlargement, or co- 

 lour under the throat, is furnished with the same kind 

 of scales as those on the ridge of the back. This 

 species is very common in all the warmer parts of 

 America ; and it is not only very inoffensive, but of 



