Page:VCH Hertfordshire 1.djvu/221

 CRUSTACEANS The student of Crustacea will find in this county much more to interest him than might be expected from the printed scientific records. Those indeed which refer to this branch of its fauna are, with one ex- ception, meagre in the extreme, not devoting to the subject more than three or four brief and rather casual notices. In his ' Notes on the River Rib from Standon to its Junction with the Lea,' Mr. A. G. Pullen, F.Z.S., writes that, ' of crustaceans, the crayfish or crawfish, Astacus flu'viatilis, is frequently met with at all parts of the Rib, and is especially abundant near Letchford.' ' Mr. John Hopkinson, F.L.S., has kindly found for me a notice of its occurrence in the river Gade, 8 and Mr. A. E. Gibbs, F.L.S., after telling me that ' crayfish are to be found in the river Lea in the neighbourhood of Wheathampstead,' very obligingly went more minutely into the question of the distribution of the species in that neighbourhood. The result of his further enquiries was as fol- lows : ' I am told,' he says, ' that it is not to be found higher up than (i.e. on the Luton side of) the Harpenden Great Northern Station, and that it is found from there to Brocket Hall. My informant, Mr. Henry Lewis of St. Albans, tells me it is not so abundant as it used to be, and he is of opinion that the young are eaten by the trout which he says are more numerous than formerly. The crayfish appears to be very local. Although fairly common in the Lea, I cannot hear that it has been found in the Ver, although both streams rise from the chalk and flow through similar country within a few miles of one another. Both Mr. Lewis and his brother, Mr. Arthur Lewis, have tried without success to intro- duce it into the Ver. Mr. Arthur Lewis says he once turned one hundred dozen into the Ver near St. Michael's Mill, St. Albans, but they seem to have entirely disappeared, only one, which was subsequently taken in an eel trap, having since been seen.' Facilities for obtaining the species in question are of no little value, since a mastery of the details of structure in this one typical form may be made the basis, as Huxley has shown, of a sound zoological education. Such a mastery will cer- tainly be helpful in an extraordinary degree to any one who wishes to examine crustaceans in general and the Malacostraca in particular with an understanding mind, and with insight prepared to find something like order and unity of plan in the mighty maze of their innumerable diver- sities. It is worth remarking that the technical name of the species is more correctly given as Potamobius pallipes, reserving the generic name Astacus 1 Trans. Herts Nat. Hist. Soe., edited by John Hopkinson, F.L.S., F.G.S., vol. ii. p. 136 (1884). 181
 * Tram. Watford Nat. Hist. Sac., vol. ii. p. 126 (1879).