CRUSTACEANS attained by the common prawn, is certainly very unusual for the Pala- monetes. Like the eels entrapped in the pits at Rome, it may in an unusual situation attain an unusual size. It may find congenial food and be free from harassing foes. That condition of things helps one to grow fat. As to the incidental sarcasm on the paucity of north Norfolk naturalists, it may in itself have been well deserved, but there is no coast far or near on which naturalists can hope to compete in numbers with the prolific prawn. Mr. Skertchly's own argument is invalidated by one startling inconsistency, since he first affirms that 'the ova are carried by the females until they hatch,' and presently after- wards sums up in favour of a supposition that the ova had been buried in the silt and lain dormant for an enormous period. He can scarcely intend that they were buried with the parent and survived the unpleas- ing contiguity of her decay. He speaks also of the silt affording plenty of water for their preservation. But it is, I believe, the fact that crus- tacean ova which are known to retain vitality for a long time without hatching out belong exclusively to the Entomostraca, and that they are preserved in dried mud, not in moist. The life history of such species has been adapted to their residence in water-basins which are liable to complete evaporation, to be followed by replenishing at a future season. No such expedient could be necessary for the prawn. But, where strong springs can rise in a pit, there seems to be no reason why the tiny larval prawns should not be carried safely along with the water. At any rate, the survival of malacostracan eggs during thousands of years cannot be accepted on existing evidence. Nearly related to the shrimps and prawns in appearance, and per- haps also in fact, are the Schizopoda, the order of the cloven feet. They are so called because many of their legs have two branches. But this is the case also with lobsters and many other crustaceans in their juvenile stages ; and a few of the Macrura retain the second branch even in adult life. In the pleon, moreover, double-branched appendages are rather the rule than the exception. Of schizopods, Norfolk has at least one on record — the pretty and delicate, black-eyed, almost transparent Gastrosaccus sptnifer (Goes). The hind margin of its carapace forms an elegant curve, fringed within by eight acute denticles.^ Of the sessile-eyed Malacostraca, I have in my possession a speci- men of the isopod Astacilla longicornis (Sowerby), taken off Yarmouth by Dr. G. S. Brady, F.R.S., by whom also the schizopod just mentioned was obtained. Of the Isopoda, it may suffice here to remark that the county is sure to yield by land and water a long list of species to any naturalist who will, with moderate diligence, search for them. Of another sessile-eyed group, the Amphipoda, much the same may be said. Of these, Metzger's catalogue contains the following names : Dryope crenatipalmata^ Bate; Noenia excavata. Bate; Aora gracilis. Bate; Micro- deutopus anomalus, Rathke ; Ampelisca tenuicornis Lilljeborg ; Melita obtusata ^ A. M. Norman, in Br'ithh Aisociat'wn Report for 1868, p. 268 ; Stebbing, in Annals and Magazine of Natural History for August and October, 1880. 191
