Page:VCH Bedfordshire 1.djvu/137

 CRUSTACEANS straight, the surface smooth, variously banded with pale yellow and green. 1 In Candona Candida the lower margin is sinuated, especially in old examples and adult males, and the surface of the shell is smooth, pearly or yellowish white, with darker yellow cloudings towards the dorsal margin.' 2 Of the Copepoda, Dr. Brady in his Revision of the British Species of Freshwater Cyclopida? and Calanida attributes to Bedfordshire two species, both from Pavenham and both on Mr. Scourfield's authority. They are both extensively distributed species, Cyclops bicuspidatus, Claus., and Diaptomus castor (Jurine), the former assigned by Brady to the family Cyclopidas, the latter to the Calanidas. 3 The genus Diaptomus, Westwood, should rather be included in a family Diaptomidas, of which it is the earliest and apparently the most extensive genus, comprising three or four scores of species. The range of D. castor is stated to be the whole of Europe, its occurrence in North America also having been reported, but not thoroughly ascertained. The length of a specimen varies from a twelfth of an inch to an eighth or even a seventh. Cyclops bicuspidatus is smaller still, as it reaches its upper limit in a twelfth of an inch, while starting from a nineteenth. In Diaptomus the first antennae are twenty-five jointed ; in Cyclops the number of joints in these appendages varies from six to eighteen, reaching seventeen in C. bicuspidatus. According to Mr. A. R. Thompson's paper above quoted many species of fish frequent the waters of the river Ouse. The supposition therefore is well warranted that in the same waters parasitic Copepoda frequent those fishes. It is indeed quite certain that the hitherto unre- corded crustaceans of Bedfordshire would fill a far longer catalogue than can be composed of those which have as yet been publicly noticed. 1 Trans. R. Dublin Soc. ser. 2, iv. 85. 8 Brady, Trans. Linn. Soc. (London, 1870), xxvi. 383. 3 Nat. Hist. Trans. Northumberland, Durham and Neuicastle-ufon-Tyne (1891), vol. xi. pt. I, pp. 79, 94-