A HISTORY OF ESSEX county, makes the following observations : ' Common at all my stations. Though sometimes free from such things, it is very commonly much covered by small sponges, ascidians, and polyzoa, which seem to be growing on the shell ; but, in some cases, many portions of the broken leaves of Zostera marina are so attached as to make it almost certain that they were intentionally so fixed by the animal.' According to the generally accepted rules of zoological nomenclature this species is more correctly called Macropodia rostrata (Linn.), the name of Linnasus being added in parenthesis to indicate that he is responsible for the specific name rostrata, but that the generic name Macropodia was assigned by a later hand. The true names of some of our crabs are by no means easy to determine. But those who scoff at zoologists on this account will perhaps find themselves at a loss to tell the surnames of the kings and queens of Europe or even those of the last and present sovereigns of their own country. The two crabs which Mr. Lovett follows Bell in calling Pisa tetraodon and P. gibbsii are called by Adam White respectively Arctopsis tetraodon (Pennant) and A. lanata, Lamarck, while Mr. E. J. Miers calls the latter P. (Arctopsis} tribulus (Linn.). The American writer, Miss M. J. Rathbun, a high authority on the subject, thinks that Lamarck's genus Arctopsis was too vaguely defined for identification. In that case the two species will become Blastus tetraodon (Pennant) and B. tribulus (Linn.), the generic name Blastus having been established by Leach for tetraodon in precedence of the name Pisa which at the same date he published for the other species. 1 Hyas araneus (Linn.) has an extensive range, being not only a typical Essex ' spider,' but being found large and fine and plentifully in arctic waters. Dr. Sorby says : ' This is common all along the coast. It is often so much covered by ascidians, sponges and other objects either growing or dead that when creeping on the bottom of an aquarium it can scarcely be recognized as a crab.' H. coarctatus, Leach, is usually smaller and descends into deeper waters, but otherwise so resembles its frequent companion as to lie under some suspicion of being a variety of it rather than an independent species.* According to Dr. Sorby's notes Cancer pagurus, Linn., the common eatable crab, may be included in the Essex fauna, for ' though seldom if ever dredged in the estuaries or near the shore it is caught by fishermen outside.' The aloofness of the great crab is compensated by the fami- liarity of the smaller eatable crab, Carcinus mcenas, for ' this is extremely abundant everywhere along the coast and in the estuaries.' Of Portunus bolsatus, Fabricius, Dr. Sorby says : ' This is fairly common in the Crouch but less abundant elsewhere.' Of the Macrura anomala two very generally distributed British species are reported by Dr. Sorby. Of the common hermit crab, Eupagurus bernbardus (Linn.), he says : ' This is very abundant off Mersea and also found at most stations. The colour of the animal and of the bunch of eggs is well preserved when mounted as a lantern slide 1 Edinburgh Encyclopedia, vol. vii. p. 431 (1814). 2 Ann. Nat. Hist, ser. 7. vol. v. p. 2 (1900). 206
