Mr. Westwood on Th;ysa7mra. 89 XX. Thysanuree Hibernicae, or Descriptions of such Species of Spring-tailed Insects (Podvira and Lepisma, Linn.,) as have been observed in Ireland ; by R. Templeton, Esq., R.A., Corj'. 3Iember of the Natural History Society of Belfast : with Introductory Observations upon the Order, by J. O. Westwood, F.L.S. Sfc. [Read June 2, and July 7, 1834.] Introductory Observations upon the Thysanura, by J. O. Westwood. My friend Robert Templeton, Esq., previously to his departure from England, placed in my hands, for the purpose of its being submitted to the Entomological Society, the following paper, containing de-scriptions of various species of Thysanurous insects which he had obseiTed in Ireland, accompanied by numerous figures, allowing me to make such additional remarks thereon as appeared serviceable by way of introduction. If we look at the Thysanura merely as an order of animals whose characters and distinctive peculiarities have hitherto been greatly neglected, the attempt to investigate their structure and specific dif-ferences could not fail to meet with approval ; but there are other circumstances which render the group of insects in question more especially worthy of attention. Firstly, from the rank which they hold amongst annulose beings, being one of those qnastiones vexatcB which it is most desirable should be set at rest, and which it is na-tural to suppose can only be done by a series of minute investiga-tions : thus, whilst Latreille and Leach consider these animals as true insects, Mr. MacLeay removes them far asunder, and places them with the Centipedes, Worms, and Lice in his class Ametabola. In the next place, these insects offer a very valuable field of in-quiry from the great modification which the various parts of the mouth undergo in the different groups, and which, when thoroughly investigated, may perhaps lead to the solution of those interesting questions respecting the real analogies of the parts of the mouth amongst the Myriapoda, Arachnida, and Crustacea, respecting which at present scarcely any two entomologists are agreed. In some of these animals we find a development of the trophi as great as in some of the most perfect of mandibulated insects ; whilst in others the mouth is so obscurely organized that neither Latreille nor Savigny has been able to trace its formation.