MEMORANDA. 



SI 5 



marked by a diamond, to which the focus must be first 

 directed. A little practice will soon lead to dexterity in 

 estimating' the position of the object when the slide is on the 

 stage, and in making a touch or a line of colour thereon as a 

 guide for the position of the ring ; the work can be examined 

 under the microscope, and corrected and finished in any 

 convenient position. A red ring painted outside the blue 

 will render it more conspicuous, and assist observation when 

 under the microscope ; the colour should be used rather thick, 

 and the whole should have a slight protecting coat of gold size 

 or varnish. As objects are mounted for other purposes than 

 to furnish neatly the drawers of a cabinet, the facility in 

 using slides thus permanently marked will outweigh the 

 objections to the unsightly appearance. — J. H. 



ITIenioranda on the Eiuployiuent of Artificial !Sea-Water in Marine 



Aquaria. — Early in the summer of last year I commenced some 

 experiments on artificial sea-water, made according to the 

 formula proposed by Mr. P. H. Gosse ; the ingredients in 

 the proper proportions having been procured from Mr. Wm. 

 Bolton, 146, Holborn Bars, London, In it I have successfully 

 maintained alive the following marine productions : — 



Animals. 

 Zoojihytes. 



1. Clava multicornis. 



2. Hydractinia echinata. 



3. Actinia Mesembryanthemum. 



Mdllusca, 



26. Cynthia momus. 



27. Pecten opercularis. 



28. Doris pilosa. 



4. „ crassicornis. 



5. „ bellis. 



6. ,, parasitica. 



7. „ Dianthus. 



8. ,, anguicoma. 



9. ,, clavata. 



10. „ Aurora. 



11. Anthea cereus. 



12. Caryophyllia Smithii. 



13. Sertularia polyzonias. 



14. ,, filicula. 



15. „ piimila. 



16. Flustra membranacea. 



17. Bowerbankia imbricata. 



18. Vesicularia spinosa. 



Annelides. 



19. Serpula oontortuplicata. 



20. „ triquetra, 



21. Sabella ? 



22. Terebella conchilega. 

 28. Spio vulgaris. 



24. Nereis ? 



25. Pontobdella muricata. 



29. ,, tuberculata. 



30. Eolis coronata. 



31. Nucula cristata. 



32. Lamellaria perspicua. 



33. Nerita ? 



34. Littorina littorea, 



35. Rissoa ? < 



36. Trocbus zizyphinus. 



37. Purpura lapillus. 



38. Chiton fascicularis and C. 



lasvis. 



Cirrhipedes. 



39. Balanus balauoides. 

 40, 



Vegetation, 



41, Ulva latissima. 



42, Enteromorpha compressa. 



43, Cladopora ? 



44, Phyllophora rubens, 



45, Bryopsis phuiiosa. 



