384 ANALOGICAL KESEMBLANCES. Chap. XIIL 



cut paradox, that the very same characters are analogical 

 when one class or one order is compared -with another, but 

 give true aflniities Avhen the members of the same class or or- 

 der are compared together: thus, the shape of the body and 

 iin-likc Hmbs are only analogical "when whales are compared 

 AviLli fishes, being adaptations in both classes for swimming 

 through the water; but the shape of the body and fin-like 

 limbs serve as characters exhibiting true aflinity between the 

 several members of the whale family ; for these cetaceans 

 agree in so many characters, great and small, that we cannot 

 doubt that they have Hiherited their general shape of body and 

 structure of limbs from a common ancestor. So it is with 

 fishes. 



The most remarkable case of analogical resemblance ever 

 recorded, though not dependent on adaptation to similar con- 

 ditions of life, is that given by Mr. Bates with respect to cer- 

 tain butterflies in the Amazonian region closely mimicking 

 other kinds. This excellent observer shows that in a district 

 where, for instance, an Ithomia abounds in gaudy swarms, 

 another butterfly, namely, a Leptalis, is often found mingled 

 in the same flock, and so closely resembles the Ithomia in 

 every shade and stripe of color, and even in the shape of its 

 wings, that jNIr. Bates, with his eyes sharpened by collecting 

 during eleven years, was, though always on his guard, con- 

 tinually deceived. When the mockers and the mocked are caught 

 and comjiared, they are found to be totally different in essen- 

 tial structure, and to belong, not only to distinct genera, but 

 often to distinct families. Had this mimicry occurred in only 

 one or two instances, it might have been passed over as a 

 strange coincidence. But, if we proceed from a district where 

 one Leptalis imitates an Ithomia, another mocking and mocked 

 species belonging to the same genera, equally close in their re- 

 semblance, will be found. Altogether no less than ten genera 

 are enumerated, which include species that iinitate other but- 

 terflies. The mockers and mocked alwaj's inhabit the same 

 region ; we never find an imitator living remote from the 

 form which it imitates. The mockers are almost invariably 

 rare insects ; the mocked in almost every case aboimd in 

 swanns. In the same district in which a species of Lcjitalis 

 closely imitates an Ithomia, there are sometimes other Lejn- 

 doptera mimicking the same Ithomia ; so that in the same 

 place, species of three genera of butterflies and even a moth 

 are found nil closely resembling a butterfly belonging to a fourth 



