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CRUSTACEANS dae afforded some of the species well known in the literature of the subject, but not always on that account very easy to name or discriminate with certainty. Two species with the first antennae seventeen-jointed appear to agree with Cyclops signatus, Koch, and C. vicinus, Uljanin, as determined in Dr. Brady's ' Revision of the British Species of Freshwater Cyclopidae.'" The former of these according to Mr. Scourfield ^ should rather be called C.fuscus (Jurine) ; the latter he regards as a mere variety of C. strenuus, Fischer, which, he says, may be found indifferently in the open waters of large lakes or in the smallest of pools. ' Corresponding to this diversity of habitat is its remarkable variation, which has led to the formation of several so-called species, e.g. C. vicinus, C. abyssorum, etc. In the present state of our know- ledge, however, these cannot be considered as good species, scarcely even as permanent varieties, and it seems best, therefore, to group all these forms under the one name, C. strenuus^ as is done by several recent writers, e.g. Schmeil, Richard, Mrazek, &c.' From both the preceding species, however we name them, C. serrulatus, Fischer, another Herefordshire capture, is well distinguished by its twelve-jointed first antennae, and similarly we have C. kaufmanni, Uljanin, separated from the other three by having the first antennae ten-jointed. In our specimen as in those figured by Uljanin and Brady, the joints i, 2, 6, 7, 10, are superior in size to the joints 3, 4, 5, 8 and 9. In this species according to the two authors just mentioned it is characteristic that all the branches of the swimming-feet are two-jointed. This is true of three of the pairs in our specimen, but one of the pairs has both branches distinctly one-jointed. The little fifth feet are two-jointed. The caudal rami are very short, but it must be admitted that they agree better with those figured for C phakratus, Koch, than with their own por- traits. C phaleratus itself has ten-jointed antennae, but the sizes of the joints differ from those in C kaufmanni, the second antennae are also different, and the fifth feet are one-jointed. It is necessary to give precise particulars in regard to C. kaufmanni, because it appears to be an exceptionally rare species. In 1891, Dr. Brady only knew of its having been found in two British localities, by Norman in Lambton Park, Durham, and by Brady him- self in Minstead Mill Dam, Hants. He adds : ' it has not been noticed so far as I know by any other author since its publication by Uljanin.' *' In the very scantiness of this catalogue there is one redeeming feature. The local naturalist whose entfiusiasm is first awakened to explore the wells and weedy waters, the gardens and woodlands, the old walls and quarries of this county for their carcinological treasures, is sure of an unexhausted territory for his researches. Beyond all question there are numbers of species for him to find, and almost every one of his discoveries will be a new record for Herefordshire. " l^at. Hist. Trans. Northumberland, &c. xi, pt. i, pp. 68-120 (1891). " Joum. Quekett Micros. CM (ser. 2), vi, p. 133 (1895). " Trans. Nat. Hist. Northumberland, &c. xi, 90, iad Uljanin, Reise, p. 38, pi. ix, fig. 1-5 (1875). 121 16