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Show 560 REV. T. R. R. STEBBING ON CRUSTACEANS [May 22, of the figures given by Milne-Edwards this lobe does not reach beyond the telson, and though described as very large is represented as comparatively long and narrow. Unless the type specimen of C. typa could be recovered and examined, it would be impossible without rashness to ignore the distinctions which Guerin-Meneville has drawn between it and C. emarginata. But they are not quite so formidable as at first sight they appear. It is not very easy to induce specimens of C. emarginata to lie flat, and when not flattened they have that much inflated (" tres-bombe ") appearance which Milne-Edwards describes. Their eye? are in fact very wide apart, and though the breadth of the head in comparison with the length will not answer Milne-Edwards's figure or description, in his figure there is foreshortening to be considered, and in his description we cannot be sure between what points he measured the head-length. He gives both a dorsal and ventral view of the animal, in the latter of which the last segment of the pleon has its apex protruding rather sharply beyond tbe uropods, whereas in the former the apex is more broadly rounded and enclosed by the uropods. It is obvious, therefore, that no particular stress can be laid on figures so variable relating to the same object. In regard to the extension of the first antennae beyond the peduncle of the second, it should be noted that this is much less considerable in small specimens of C. emarginata than in large ones. Of the remarkable bend in the basal joints of the second and third peraeopods (4fch and 5th limbs of the peraeon), the ventral view of C. typa shows indeed no trace ; but neither does Pfeffer in his careful and elaborate account of C. emarginata take any notice of this peculiarity, although he explains that in all the limbs of the peraeon the first and second joints are more or less firmly coalesced, but, except in the first pair, plainly distinguishable. The feature to which Guerin-Meneville called attention is in reality not an arching of the first joint of the limb, but rather a geniculate connexion between the coalesced first and second joints; a detail much less likely to attract attention in a ventral view of a small specimen than in a lateral view of a large one. Against identifying C. typa with C. emarginata there still, however, remains a stumbling-block in the shape of the uropods. Of these Milne-Edwards gives a separate figure, in which the inner lobe is much longer thau broad, with a narrowly rounded apex ; whereas in C. emarginata this lobe is little broader than long, and has an oblique, slightly emarginate apical border, of which the inner angle does not reach the end of the pleo-telson, but the rounded outer angle reaches well beyond it. It is at least possible that we have here the explanation of the discrepancy in the two figures of C. typa, the artist in the ventral view observing the inner angle of the uropods, and the outer angle in the dorsal view. It is further possible that in the separate figure he had the uropod angularly placed, so that the long distal margin appeared as part of the outer side. That all this argues more carelessness in the figures than ought to be imputed to a work so high in reputation |