TRACHEARLffi. 



471 



gi"UuluS 



'■, 111 1 ^ t . 1 - 



or rounded, and generally soft : in some males, it is narrowed behind into a cylindrical tail. The 

 number of eyes is either two or four, and even six, according to Miiller. 



Eylaix, Latr., has the chelicene terminated by a moveable claw. A. extendens, Fabr. 



Ilydraclina, Latr., has the mouth composed of plates, fomiiner a projecting 

 sucker, and the palpi have a moveable appendage beneath the extremity. 

 A. geographicus, Fabr., A. globator, Fabr. 



Limnochares, Latr., has the mouth sucker-shaped, but the palpi are simple. 

 A. aquations, Linn. [Other species of these water-mites have been described 

 by M. Theis, in the Annates dcs Set. Nat. for 1832]. 



[From the very valuable discoveries lately made by M. Dujrcs, it appears 

 that these water-mites undergo metamorphoses, accompanied by a complete 

 Change of form, the lame having a very large head and six legs, whilst the 

 pupa' are inactive, attaching themselves, by a single pair of legs, to the 

 bodies of other aquatic insects, and consisting, as it were, simply of an oval 

 bag with a narrow neck, the insect in this state having been formed, by 

 M. V.Andonin, into the genus Achlysia, and specifically named A. Dytici, from taking up its residence beneath 

 the elytra of the Water Beetle (Dyticus marginalis). They also attach themselves to the slender filaments com- 

 posing the tails of the Water Scorpions {Nepa and Ranatra).] 



Other Mites {Micropthira, Latr.) differ from all the foregoing, in having six legs. They are all parasites. 



Caris, Latr., lias the sucker and palpi distinct; the body rounded, very flat, and covered with a scaly skin. C. 

 vetpertilionit, Latr. On Bats. 



I'M. V.Andonin has figured an insect which he considers may be identical with Caris vespertilionis, in the 

 Annates des Set. Nat., 1832 ; and which, notwithstanding its possessing only six legs, he considers as more pro- 

 perly belonging to the genus Argas.] 



Leptus, Latr., has al>o a sucker and palpi, but the body is soft and ovoid. A. aii/iimnalis, Shaw (Misc. Zoo!., 

 vol. ii. pi. 42), is very common, in autumn, upon grass and other herbage. They crawl upon our bodies, and in- 

 sinuate themselves into the skin at the roots of the hairs, occasioning as painful an irritation as the itch. [It is 

 tin- well-known Harvest Bug], but it is bo minute as rarely to be observed. 



The other species are found upon diflerent insects, and enter into the division of the Trombidet hexapode* of 

 Hermann. T. (ntectorum, Herm., T. lAbeUubs, ilerm., T. CulicU, Herm., &c. 



via, And., here placed by Latreille, is now proved to be the immature state of Hydrachna.] 



Atoma, Latr., has neither suckers nor palpi visible ; the mouth consists only of a small orifice, situated upon the 

 breast; the body is soft, oval, with the feet short. Aeant.i parasiticus, Herm. 



Ocy/nte, Leach, belongs to this section, from the number of its legs ; but, according to him, it has mandibles. 

 0. rubra, Leach. Upon Tipulae. 



[From the recent observations of Audouin, Duges, and others, it seems questionable whether this terminal sec- 

 tion of the Mites can be retained, consisting, as it is now supposed to do, entirely of the young states of various 

 groups of Acaridae.] 



[The Senator Van Ileyilen has lately published a distribution of the Acaridrc in the Iritj and many very minute 

 gpecies are figured in the continuation of Panzer's Fauna lnsectorum Germniii.e. by Herrick Schiffer, distributed 

 into many new genera. At the same time, M. Dnges, in his more elaborate ami complete memoir, published in 

 the Annates da Si L Vat., has revised the entire group, dividing it into numerous genera, arranged into the fol- 

 lowing groups:—!. Trombidiei ; 2. Hydrachniei ; 3. Uamasei ; 4. Ixodei ; 5. Acarei ; G. Bdellei ; and, 7. Oribatei.] 



THE THIRD CLASS OF ARTICULATED ANIMALS FURNISHED WITH 



ARTICULATED LEGS,— 



[NSECTS (Insbcta),— 



Which have articulated legs, a dorsal vessel occupying the place of the vestige of a 

 heart, but without any branch for circulation*; which respire by means of two principal 



• Anatomist! are divided in tin ir opinion aa to the nature <f tin* 

 . many rtgardlof it at a distinct heart, « blUt othera [Inclndlnji 

 r, arboec opinion appears t<> have been fully confirmed by the 

 researches of M. icrted in ihc flfcaaoerei dn Alut. d I/ttt. 



,\ ■ !. ny ii this <|U»lilr. S.>nie rrcrtit observation! appear to eata* 



blish the ulftMICI •>* several small vesscli, but betide* that, Lnll rir- 

 iiil'itM'ii mul Dt *ery partial, as Insects differ inatrn.-illy fr<>m the 



Cnstacea, tbe bl> ae! nol returning to tbe heart Act anting i" H 



u quoted by Mrauia {Uuiletin. dt L'mttrri Ftruutu , the d..r»al ve»*cl 



li the true hcrt of insect*, being, aa In the hJffcsff animals, the 



r k '<»iiof tbi blood, which. Insteaitof being eontalaea 1 In rteotlftj 



extend* through the general cavilr .<f if.r bodf, t f i» heart occupic* 



Ihc entire length »f the bulk of the abdomen, and terminates anlt- 



riorljr in a single artery, wall h Li tut '• tLe 



-.. tac bead, whence it returns to tbi nbdoanoa bribe »er« 



effect of Its U a La the bead, to re enter the heart ; ». 



In tin* thut the entire circulation Oi tt"* I'l .-I .'f || ■», and 



which arc consr iuentl? destitute cl ft .. V. Mraca*. 



