832 



ous-rooted herbs, having monandrous flowers, and 

 belonging to Scitaminece. This is the well-known 

 ginger, so useful to the inhabitants of the countries 

 where it grows wild, and also to every other part of 

 the known world, as a wholesome spice. It is culti- 

 vated everywhere in India, and forms an important 

 article in commerce. In Britain it is raised in very 

 great perfection on hotbeds, for the purpose of making 

 a preserve in its green and soft state. 



ZIRCON. This rare and beautiful mineral de- 

 rives its name from the French word jargon, which 

 was originally applied to all those gems, which, on 

 being cut and polished, had somewhat the appear- 

 ance of the diamond. The common Zircon approaches 

 to a grey colour, and is mostly procured from the 

 island of Ceylon. The primitive form of Zircon, 

 according to Haiiy, is composed of two four-sided 

 pyramids, applied base to base. The accompanying 

 figures furnish good views of its ordinary crystallised 

 forms. 



ZIRCON ZYGCENID^E. 



Zircon is found in company with the hyacinth, 

 with which it is frequently confounded, but from 

 which it materially differs in its colour and crystal- 

 lised form. From the diamond it is distinguished by 

 its crystallisation, greater weight, and conchoidal 

 fracture ; and from most other gems by its peculiar 

 power of refraction. These characteristics can only 

 be easily indicated by absolute comparison ; and 

 this points out the great advantage of cabinet col- 

 lections of specimens in mineralogical pursuits. In- 

 deed, the great increase of knowledge in this branch 

 of science, may be mainly traced to the increase of 

 " natural history collectors," as the practical students 

 in the great Book of Nature are usually called. An- 

 other circumstance, and one that should never be lost 

 sight of in tracing the progress of mineralogy, is the 

 facility for investigation on a large scale furnished by 

 the vast gallery now opened to the public in the Bri- 

 tish Museum. We have there spread out before 

 us many hundred thousands of specimens procured 

 from every quarter of the globe ; and if the descrip- 

 tive accounts prefixed were but a little fuller, it would 

 still more facilitate the researches of the student. 



ZOEA (Bosc). A very curious genus of small 

 crustaceous animals, respecting which great diversity 

 of opinion has been entertained amongst crustaceo- 

 logists : the carapax is large and nearly globose, 

 armed with remarkably long spines in front and be- 

 hind, as well as at the sides ; the eyes are very large; 

 and placed on footstalks ; the apparent organs of 

 locomotion are two pairs of large bifid articulated 

 members ; but a very careful examination discovers 

 ten other rudimental legs (the anterior pair being 

 cheliferous) within the shells ; the antennae are four 

 in number; and the abdomen long and furnished 

 with a terminal apparatus for swimming. Latreille 



has placed these insects, which are of very small 

 size, amongst the branchiopodous Erdromo&taca ; but 

 Mr. J. V. Thompson has, in several memoirs, as- 

 serted that they are only the larvae state of some of 

 the crabs. 



The assertions of this writer have need of much 

 confirmation, and indeed Dr. Rathke, to whom Mr. 

 Thompson is opposed in toto, has recently published 

 a note, which will, we think, in conjunction with his 

 announced Memoir, completely overthrow Mr. 

 Thompson's statements, which are certainly made 



without any of that precision which is so obviously 

 requisite in such a matter. The species here figured 

 is from Mr. Thompson's work ; it is exceedingly mi- 

 nute (the size being indicated in the scroll), and 

 was discovered in the sea near Cork, and is asserted 

 by him to be the larva of the common edible crab. 

 ' ZYGODACTYLI. Birds which habitually have 

 two toes to the front and two to the rear, without 

 any reversing. They are the same with the Grim- 

 percs, Sconsores, or climbers of different authors. 

 See the article BIRD, and the references therefrom, 

 which are well worthy of attending to, as these are 

 among the most peculiar, and therefore the most in- 

 teresting, of all the birds. 



ZYGCENID^E (Stephens). A family of beautiful 

 lepidopterous insects, placed by Linnajus with the 

 Sp/iingcs, on account of the similarity in the structure 

 of the antennae, but having a much nearer relation to 

 some of the moths. The antenna? are generally 

 thickened in the middle, and slightly pectinated, 

 especially in the males. The wings, when at rest, 

 are deflexed at the sides of the body, and very much 

 varied in their colours, often offering glass-like spots ; 

 the abdomen is not tufted at the tip. The caterpillars 

 are pilose, without any caudal appendage ; they arc 

 not enclosed in a case, and feed on different legumi- 

 nose plants. When full-grown, they form a silken 

 cocoon, which they attach to the stern of different 

 grasses, of a spindle-shaped appearance. They fly in 

 the hot sunshine. Many of the species are exotic, 

 few only being found in this country ; these compose 

 the two genera, Zygcena of Fabricius and Proem of 

 Fabricius (Ino, Leach); the former comprises the 

 Burnet moths (which are of a fine blue-black colour 

 with scarlet spots), and the latter is composed of a 

 single species known to collectors under the name of 

 the green forester (Ino statices, Leach). They are to 

 be found in the summer months sporting on the wing, 

 in the hottest sunshine, over grass, &c. 



