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 A HISTORY OF KENT may be fewer, but the mystic nineteen is a number avoided. There are three principal divisions, the Branchiopoda named from their branchial feet, the Ostracoda with carapaces in the fashion of bivalve shells, and the Copepoda called oar-footed because their legs are locomotive, in contrast to the Cladocera which swim by help of their second antennae. The first subdivision of the Branchiopoda consists of the Phyllopoda, the ' leaf-footed.' Of this notable company there are three sets. One of these, with which we are not here concerned, is called Conchophylla, because all the leaf-like feet are concealed in a bivalved shell-like carapace ; another is called Gymnophylla because all the ' leaves ' are exposed to view, and a third is named Notophylla because a large dorsal shield covers many but not all of the footbearing segments. This last is or was illustrated in Kent by the wonderful Apus cancri- formis, Schaeffer. The species is described by Baird as ' about two inches and a half long, and one inch and a half in diameter ; of a brownish-yellow colour, clouded with marks of a deeper hue.' There are sixty pairs of feet, the structure of which is not a little complicated, comprising on the inner line a maxilla-like basal lobe followed by five subjointed ' endites,' and on the outer two ' exites,' namely, a flask- shaped gill and a simple triangular flabellum or accessory gill. The eleventh pair of feet carries the ovisacs in the female and the genital openings in the male. Behind this the caudal part of the animal has segments with several pairs of appendages to each and several segments without any appendages, the last segment of all however being provided with two long jointed streamers.* Herr Stadt-Secretarius Klein first introduced this remarkable creature to science by sending it, with a good drawing and Latin description, from Dantzic to the entomologist Job. Leonhard Frisch, who published it in 1732.' Klein, it appears, soon afterwards wrote about it to Sir Hans Sloane, and in connexion with this letter, the following paragraph is worth quoting from Baird's long and excellent discussion of the species : — ' About the same time a number of specimens of the same animal were found in Kent by the Rev. Mr. Littleton Brown, F.R.S., who, in August 1736, sent a specimen, with a letter to Dr. Mortimer, then secretary to the Royal Society, and which is published, along with Klein's letter to Sir Hans Sloane, in the Philosophical Transactions for 1738, No. 447. " I brought it," he says, " from a pond upon Bexby (Bexley ?) Common, where great numbers have been observed for these five weeks past. The pond was quite dry, the 24th of June, but upon its being filled with the great thunder-shower, upon the 25th, within two days the pond was observed to swarm with them, by a farmer watering his cows there." '* Of the Gymnophylla Baird reports finding the ' Fairy Shrimp,' » British Entomostraca, p. 30 (1850). » See Packard, U.S. Geological Survey, p. 315 (1883). i" Beschreibung von allerlei Insecten in Teutschland, pt. x. p. I. < British Entomostraca, p. 29. 252