304 



MYGALURUS MYOPOTAMUS. 



web of very fine texture resembling muslin. The 

 cocoon of the same insect, or rather the egg-case, is 

 of the size and shape of a large nut, the outer en- 

 velope being composed of silk of the same kind as its 

 nest, arranged in three layers. It appears that the 

 young are disclosed within this case.and there undergo 

 their first moulting. M. Goudot stated to Latreille 

 that he had extracted as many as a hundred young 

 from one of these cases. There are several species 

 of these insects in Brazil, East India, and the Cape of 

 Good Hope ; and M. Dufour has also found one 

 even in the arid deserts of Moxenta, in Spain. 



In the second division of the genus Cteniza, (La- 

 treille), the Chelicerce are furnished at the tip with a 

 series of movea'ole spines, and the tarsi are less 

 strongly cushioned, so that the claws are not hidden. 



The type of this division is the Mygale ccementaria 

 (Latreille; Araignee maponne of Sauvages), or the 

 mason or trap-door spider, so named on account of 

 the curious structure of its nest, as observed by Sau- 

 vages, Dufour, and more recently by Audouin, who 

 has published an interesting account in the " Annales" 

 of the French Entomological Society. These spiders 

 dig in the dry and mountainous districts of the south 

 of Europe subterraneous galleries, of a cylindrical 

 tortuous form, to the depth of many inches (sometimes 

 two feet) ; they also construct at the mouth of the 

 burrow, formed of silk and earth, a move-able oper- 

 culiim, or trap-door, which is so attached as to 

 exactly fit the entry to the habitation, and to lift up 

 and down. 



These habitations are formed on an argillaceous 

 kind of red earth ; the walls are not left just as they 

 are bored, but are first covered with a kind of mortar, 

 which is subsequently coated with finer mortar, as 

 smooth and regular as though a trowel had been 

 passed over it. This coat is very thin and sott to 

 the touch ; within this is a tapestry of silk, having 

 the lustre of satin, and almost always of a dazzling 

 whiteness. These coatings render the nest imper- 

 vious to wet. But. the trap-door is the most singular 

 part of the construction, being- composed of more than 

 thirty layers of earth and web, ernboxed as it were in 

 each otiier, like a set of weights for small scales, 

 these layers of web terminating in the hinge, so that 

 the greater the volume of the door, the more powerful 

 is the hinge ; and by another peculiarity in the con- 

 struction of this nest, the strength of the hinge, and 

 die thickness of the frame, are always proportioned 

 to the weight of the door. Whenever, therefore, the 

 spider enters her nest, or goes out, the door shuts of 

 itselt Resistance is, however, experienced in en- 

 deavouring to open the door from without, and which 

 M. Audouin supposes is caused by the spider within 

 pulling down the door with her claws. Indeed, the 

 inside of the door is remarkable for a semicircle of 

 minute orifices, placed on the side opposed to the 

 lunge, about thirty in number, the object of which 

 M. Audouin considers is to enable the animal to hold 

 the door down, in. case of emergency, against external 

 force, bv the insertion of its claws into some of them, 

 the claws, as above stated, being furnished at the tip 

 with a series of moveable spines. There are several 

 of these trap-door spiders, one of which is found in 

 the Island of Naxos (C. ariana); another in Jamaica 

 (C. nidulans) ; a third at Montpellier (C. ccementaria} ; 

 a fourth (C. Sauvagesi, described by M. Audouin) 

 in Corsica ; and a filth found in various parts of New 

 South Wales, by Mr. Bennet, and described in his 



Wanderings in that Island (vol. i. p. 328). Mr. Kirby 

 has figured the Jamaica species and its nest in the 

 frontispiece to the second volume of his Bridgewater 

 Treatise, in which he has also copied M. Audouin's 

 figures. M. Dufour is of opinion that it is the females 

 alone which construct these nests, the males being 

 generally found under stones, and their structure not 

 appearing so well adapted for building as those of 

 the females. 



MYGALURUS (Lamarck). A genus of European 

 grasses, chiefly annuals, and therefore not in cultiva- 

 tion. In English botany they are called Fesluca, or 

 monsetail. 



MYGINDA (Jacquin). A genus of hothouse 

 shrubs (except one, the M. myrtifolia) belonging to 

 RhamnefB, The plants delight in a loamy soil, and 

 are increased by cuttings. 



MYLABRIS(Fabricius). A genus of coleopterous 

 insects, belonging to the family Cantharula:, having 

 the antennae eleven-jointed in both sexes, thickened 

 towards the tips, with the last joint distinct and larger 

 than the preceding ; the body is long and sub-cyliu- 

 dric, and the thorax narrow. This is an extensive 

 genus, consisting of handsomely marked species, none 

 of which are inhabitants of this country, although 

 some inhabit the more southern parts of Europe. The 

 type is the Melo'e chicorii, Linnaeus. Several species 

 are employed as vesicants, having powers similar to 

 those of the blister-fly, Cantham vesicatoria. 



MYLOCARYUM (Willdenow) is the buck- 

 wheat tree of Georgia, belonging to Ericece, formerly 

 called Cliftonia ligwtrina. 



MYOCONCH A. A genus of molluscs, established 

 by Sowerby in his Manual of Concholoyy. 



MYOPOTAMUS_The Coypou. "A genus of 

 rodent mammalia, resembling the beaver in size, in 

 the places of its habitation, and in some other parti- 

 culars, but differing from it in geographical distribu- 

 tion, and in other respects, being found only in the 

 tropical parts of America, whereas the beaver is found 

 only in the cold regions of the north. This animal 

 is very generally distributed over the warm parts of 

 South America, where it is found on the banks of the 

 streams, and chiefly, indeed, inhabiting the waters 

 where it finds the principal part of its food. The 

 first correct notice which we have of it is in Molina's 

 account of Chili, coypou being its name in that 

 country. It is also mentioned by D'Azzara, in his 

 natural history of Paraguay, under the name of 

 Qttanya; and it was also observed by Commerson, 

 (after whose death an account of it was found among 

 his papers,) as the type of a new genus, under the 

 name rnyopotamus. Commerson left a drawing of 

 the animal ; and between that and the account given 

 by the natural historian of Paraguay, the characteis 

 and relations of this addition to the rodentia of South 

 America were tolerably well made out. Long pre- 

 vious to this, the skin had been by no means an unim- 

 portant article of commerce ; but it was not until five 

 or six years of the present century had elapsed that 

 the animal itself was known, even to the naturalists of 

 Europe. For a long time the researches of those 

 naturalists were confined to the ransacking of the 

 warehouses of furriers for the purpose of examining 

 the skins ; but as no attention is paid in the procuring 

 of such skin?, to preserve the characters of the animals 

 to which they belong, the results of those examinations 

 were far from valuable ; and a long time elapsed 

 before anything else than the mere external were 



