In both these characters, but more especially in the former, the Amurland and Japanese _Astaci_ depart from both the Pontocaspian and the West American _Astaci_, and approach the _Cambari_ of Eastern North America. [Illustration: FIG. 78.—_Cambarus_ (Guatemala) penultimate leg. _cxp_, coxopodite; _cxs_, coxopoditic setæ; _pdb_, podobranchia; _bp_, basipodite; _ip_, ischiopodite; _mp_, meropodite; _cp_, carpopodite; _pp_, propodite; _dp_, dactylopodite.] In these crayfishes, in fact, one or both of the same pairs of legs in the male are provided with similar hook-like processes; while, in the females, the modification of the penultimate thoracic sternum is carried still further and gives rise to the curious structure described by Dr. Hagen as the “annulus ventralis.” [34] Kessler, l. c. In all the _Cambari_, the pleurobranchiæ appear to be entirely suppressed, and the hindermost podobranchia has no lamina; while the areola is usually extremely narrow. The proportional size of the areola in the Amurland {313} crayfishes is not recorded; in the Japanese crayfish, judging by the figure given by De Haan, it is about the same as in the western _Astaci_. On the other hand, in the West American crayfishes it is distinctly smaller; so that, in this respect, they perhaps more nearly approach the _Cambari_. Unfortunately, nothing is known as to the branchiæ of the Amurland crayfishes. According to De Haan, those of the Japanese species resemble those of the western _Astaci_: as those of the West American _Astaci_ certainly do. With respect to the _Parastacidcæ_; in the remarkable length and flatness of the epistoma, the crayfishes of Australia, Madagascar, and South America, resemble one another. But in its peculiar truncated rostrum (see fig. 65) and in the extreme modification of its branchial system, which I have described elsewhere, the Madagascar genus stands alone. The _Paranephrops_ of New Zealand and the Fijis, with its wide and short epistoma, long rostrum, and large antennary squames, is much more unlike the Australian forms than might be expected from its geographical position. On the other hand, considering their wide separation by sea, the amount of resemblance between the New Zealand and the Fiji species is very remarkable. * * * * * If the distribution of the crayfishes is compared with that of terrestrial animals in general, the points of {314} difference are at least as remarkable as the resemblances.