Transactions of the Linnean Society. 493 



" Description of a new Species of Agama, brought from the Columbia 

 '* River by Mr. Douglas;" and is from the pen of Mr. Bell, who has 

 named it, after the enterprising traveller who first discovered it, Jlgama 

 Douglasii, Ag. " poris femoralibus utrinque xx." This remarkable 

 character deviates entirely from that assigned by authours to the genus 

 with which Mr. Bell has associated it, of which the absence of femoral 

 pores forms a distinguishing mark ; but he observes that as in every other 

 respect it may be considered even a typical representative of Agama, 

 he would propose rather to alter the generic character so as to admit of 

 its reception, than to form a new genus by which it would be separated 

 from its immediate congeners. In its general form, colours, and mark- 

 ing, it very much resembles .^g. superciliosa, Ag. orbicularis, and 

 others of the same section. The representation which accompanies the 

 detailed description given by Mr. Bell is most beautifully executed. 



To the departments of Zoology which embrace the study of inverte- 

 brated animals there are but two contributions. Both of these are en- 

 tomological, and are from the pen of our correspondent, the Rev. Lans- 

 down Guilding. The first is on " The Generic Characters of Formica- 

 " leo ; with the Description of two new Species;" the distinguishing 

 characteristics of the latter of which will be found at page 599 of our 

 third Volume. The second is " An Account of Margarodes, a new 

 " Genus of Insects found in the Neighbourhood of Ants' Nests." Of 

 this paper also an analysis has been given in the Zoological Journal, Vol. 

 III. p. 600, which contains the essential particulars of Mr. Guilding's 

 communication ; yet so singular is the insect which it introduces to our 

 notice, that we cannot refrain from offering a few additional remarks. 

 As to the station in our systems to which Margarodes should be referred, 

 Mr. Guilding professes an unceitainty so absolute as to abstain from 

 offering even a guess at the order with which it should be associated. 

 Were we to venture a suggestion on this point, it would be that the in- 

 sect possesses considerable affinity with the Parasita of Latreille, in- 

 cluding the genera Pediculus and Ricinus, alternately referred by that 

 great entomologist to the Arachnida and the Insecta. With these it 

 accords in the possession of antennoe, and in the absence of true eyes. 

 The number of its feet is the same, and the structure of these organs in 

 Margarodes, to judge from the figures given in illustration of the paper, 



