December 2, 1889.] 



KNOWLEDGE 



27 



speed of their limbs, or in the sharpness of their teeth 

 and talons. 



The solitary group of mammals wliich has sought pro- 

 tection in a coat-of-mail is the one which comprises the 

 sloths, ant-eaters, and armadillos. Only a few, however, 

 of these creatures have thus protected themselves ; while 

 some, like the sloths, have sought refuge in an arboreal 

 life ; and others again, like the ant-eaters, have found 

 protection by burrowing in the ground. These mammals, 

 which are scientifically known as the Edrnlatcs. ;ire all of 

 a very low type of organization, and wiilil\ ililii rriit from 

 all other members of the class. It is, ho\\x\er, noteworthy 

 that low as they undoubtedly are, yet that they exhibit no 

 signs of relationship with the lowest of the mammal class, 

 such as the Australian duck-mole. Since, moreover, the 

 duck-mole and its allies have no coat-of-mail, it is further 

 evident that the Edentates have not inherited their armour 

 from lower forms, but that they have evolved it themselves 

 de nora. 



The Edentates having however, so to speak, once made 

 up their minds that armour is the right thing have gone 

 in for it with a will, with the result that they show some 

 of the finest specimens of plate-armour to be found in the 

 whole animal kingdom. In the comparatively small 

 armadillos of America, which are the best known examples 

 of the armoured Edentates, tlie whole of the body, with 

 the exception of the under surface, is protected by a very 

 strong bony armour, w^hich is often elegantly sculptured. 

 Thus their shoulders are encased m one solid shield, and 

 their loins in another, the two shields being connected by a 

 series of movalile transverse bands, which permit the 

 creature to roll itself up into a ball after the manner of a 

 hedgehog, and thus present a sphere of plate-armour to an 

 enemy. Still more wonderful, however, is the armour of 

 the extinct Glyptodonts (Fig. 5) of South America, m 





FlO. 5. — A GlVI'TODONT KdENTATE, showing THK C'AKArAl k. 



A, View of entire animal. «, Front end of carapace, r, Biicl^ view of 

 same, d and e. Upper and under side of sliull. K, Section of tail 

 showing caudal vertebrie inside the bony sheath. 



which the shield formed a single solid carapace, which 

 may be as much as five feet in length, and with a thick- 

 ness of more than an inch of solid bone. These creatures 

 could not, of course, roll themselves up, and they there- 

 fore bad their tails ]irotected by a coaling of bony rings 

 closely articulated together. ^loreover, some of them 

 had a breast-plate on the under surface of the body, of 

 which it is not very easy to see the necessity, since this 

 aspect would not be expo.sed to attack. The huge cara 

 paces of these (iiy)itodonts are often I'oluid on the Pampas, 

 where they are said to be used as shelters by (hr ii;iti\i s. 



One would have thought that with such an annour the 

 Ijreed of Glyptodonts would at least have lived as long as 

 the puny armadillos ; but their extinction in long past 

 epochs repeats tlie lesson that the race is not always to 

 the swift, nor the liattle to the strong. 



Finally, as a last and very original type of mailed 

 animals, w-e must mention the scaly ant-eaters, or pangolins, 

 of Africa and Asia, which (pursuing our metaphor) appear 

 to have come to the conclusion that a bony plate-armour 

 is nmch too heavy for such warm climates, and have, 

 therefore, adopted a light and elegant scale-armour com- 

 posed of overlap25ing brown, horny scales, causing them to 

 look much like an elongated cone of a spruce-fir endued with 

 life. Even, however, tliis lighter and last type of armour 

 does not appear to have been altogether a success in Ufe's 

 battle, since pangolins are comparatively scarce animals, 

 few in species, and dragging on what seems to us a 

 somewhat dull existence by the aid of nocturnal and 

 burrowing habits. 



THE COMMON FLEA. 



By E. a. Butlek. 



NOTWITHSTANDING his elevated position m 

 the animal creation, man is no more exempt — 

 humiliating though the confession may be — from 

 the attacks of personal parasites than other 

 animals ; but of the various species that link 

 their fortmies with his, and subsist upon his person, fleas 

 seem less dependent than any others upon uncleanly con- 

 ditions and habits of personal neglect on the part of their 

 host, and hence they are not restricted to the lower strata 

 of society but become a universal nuisance. The ever- 

 present desire to exterminate them, no doubt, operates 

 powerfully against their being minutely studied, and hence 

 very little seems to be generally known about their struc- 

 ture, habits, and life history, beyond what painful expe- 

 rience teaches. And yet they are really extremely curious 

 creatures, and were it not for the popular prejudice against 

 them, they would, no doubt, attract the attention they 

 deserve : it is no exaggeration to speak of them as zoo- 

 logical oddities. There are many diii'erent kinds besides 

 that particular species that infests man ; they have been 

 observed on various mammals, especially small ones with 

 thick fur, or hair, such as moles, shrews, squirrels, mice, 

 rats, dormice, hares and rabbits, as well as on dogs and 

 cats. Many birds also are infested by true fleas, in addi- 

 tion to their own proper parasites, the bird lice. The 

 species which attack these different hosts seem to be dis- 

 tinct, each animal, as a rule, supporting its own special 

 liarasite. but they resemble one another .so closely that 

 tboy form a perfectly natural family, which is called 

 l'iiii<i<l,i, horn the priiu-ipal genus ' /'»/<■.(•. On the other 

 hand, in then- most characteristic peculiarities they are 

 utterly unlike any other insects, and hence have been a 

 great puzzle to systomatists. It is not easy to find a suit- 

 able corner for them in our schemes of classification, and 

 many have got oxer the difficulty by placing them in an 

 order by themselves, which, from the apparent absence of 

 wmgs, has been called Aphaniptera (without distinct 

 wmgs). Others have, howe\er, seen ui them some affini- 

 ties to the two-winged flies, or Diptera, and have located 

 them somewhere in that order ; but here again there has 

 not been unanimity, and some have placed them at the 

 end, while others have inserted them in the body of the 

 order, followuig the Mi/ntoiiliiliilo, a family of small flies 

 which possess considerable jiuuping power, and live L:re- 

 trnriouslv amongst decaying vegetable matter, or in fungi. 



