A HISTORY OF ESSEX the pier at Harwich. Mounted in Canada balsam specimens show the structure well, and have retained the natural colour for a good many years. 12. Botrylloides leachii, Sav. Common in the Orwell just outside Essex, and I think I have also found it in the Stour. By proper management both the form and natural colour may be well preserved in un- diluted glycerine. 13. Polyclinum aurantium. In 1889 fine specimens were common in the creek east of Walton-on-Naze. Sections mounted in Canada balsam show the structure very well, and have retained the natural orange colour for many years without any apparent change. 14. Didemnum, 15. Leptoclinum, and 1 6. Diplosoma. Some species of these genera occur in the Orwell, just outside Essex, and probably could be found in the Stour and in the creeks near Walton-on-Naze. 17. Oikopleura, sp. Appendicularians are common in sievings of the sea water all along the coast. 88
