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Show 720 MR. W. F. LANCHESTER ON CRUSTACEANS [June 19, Cape Rachado, where Mr. Bedford spent some time after my return home, he obtained several examples of Matuta, a genus of which, out of the three species in the collection, only one comes from Singapore. As regards the systematic part, I have described as new 5 varieties and 7 species, and 2 of tbe species have had to be referred to new genera: one, a Leucosiid of the Oreophorus type, which is interesting because of the great lateral expansion of its carapace; the other, a small form with a very general resemblance to an Actcea, especially in the front and orbits, but with well-marked palatal ridges and other differences. As regards the common genus Thalamita, of which there are 3 species, I had hoped to be able to set at rest the question of the value of their specific characters, but was unfortunately unable to obtain sufficient specimens for comparison ; but from w hat I have myself seen, and taking Kossmann's (Zoolog. Ergebn. p. 48), and other scattered, evidence into consideration, I think it strongly probable that some at least of the species should be united-as, for example, the three in the collection, T. crenata, T. spinimana, and T. dance. Dr. de M a n (Mergui Crust, p. 78) has laid some stress on the form of the lobes of the internal angle of the eye; but these are certainly variable in the specimens I have examined. I have taken measurements of the breadth and length of the carapace of nearly all the individual examples of each species, and, but for the lack of space, would have given the length of the rostrum, lateral margins, & c , in order to make the list more complete. It is, of course, very difficult to find any constant lines of measurement, owing to the variability, in the same species, of the form of the carapace; spines, w hether rostral or lateral, are notoriously variable, and there is no necessary constancy in the straightness, or amount of convexity or concavity, of the frontal and posterior marginal lines. Under these circumstances, I have taken the following bases of measurement:-In the Oxyrhyncha, Cyclometopa, and Oxystomata, the length from the middle of the posterior margin to the middle of a line drawn from the one base to the other of the praeocular or internal supraocular (as the case may be) spines: such a line approximately defines the base of the rostrum. I have never found the pra?- or supraocular spine so ill-developed that this line cannot be traced. The breadth, in these groups, has been taken from the anterior base of the last lateral (Cyclometopa) or epibranchiiil (Oxyrhyncha) spine, or from the epibranchial angles. In the Catometopa, however, I have found myself obliged to include the rostrum in the measurement of length, and to take the breadth from the point of one external ocular spine to that of the other. None of these measurements, however, can be considered as other than approximate; I give them, as I have taken them, for w-hat they are worth. They certainly do show a variability in proportions, which, though slight in a great many species, is in others rather striking. As regards the references that are given, under each species, I |