Illustrations of British Zoology, 43 



are also, according to Poll, an eminent naturalist of Naples, 

 much larger than in man ; so that he considers the latter to 

 be to the former as hemp-seed to millet-seed. {Rudolphi^s 

 Physiology^ by How, vol.i. p. 132.) The red colour of blood 

 has been attributed to the existence of iron in it in combination 

 with phosphoric acid ; but it militates against this hypothesis 

 when we find that the white blood of the Mollusca, although 

 the contrary has been asserted, contains the same mineral 

 ingredient : for Erman has detected iron, and very probably 

 also manganese, in the blood of the Helix pomatia and Pla- 

 norbis corneus ; and Poli likewise speaks of iron in the blood 

 of A'rca glycymeris. (Rudolphi^s Physiology, by How, vol. i. 

 p. 113.) As the following analysis may probably be applied 

 with safety to the whole class, I extract the passage entire, not- 

 withstanding it repeats some particulars already noticed : — 

 " The blood of the Helix pomatia," says M. Gaspard, " is 

 rather thick, but without viscosity ; it has a faint smell, a 

 slightly saline taste, and is so abundant that each individual 

 contains not less than a drachm and a half. It is of a delicate 

 blue colour, which is neither altered nor modified by change 

 of aliment, by asphyxia, or by hybernation. It is miscible 

 with water, but of. greater specific gravity, and falls to the 

 bottom in visible streaks or entire drops. When exposed to 

 the atmosphere, it does not spontaneously congeal, like that 

 of vertebrated animals, but it separates by rest into two dis- 

 tinct fluids : the one blue, which swims at the top ; the other 

 colourless and opaque, remaining at the bottom of the vessel. 

 In a few days it decomposes with fetor [stench]. It is unal- 

 tered by muriate of barytes, and by alcohol ; is simply dis- 

 coloured by potash, and by vinegar and other weak acids : 

 but acetate of lead, nitrate of silver, and, still more, nitrate 

 of mercury, occasion a copious dense precipitate. Boiling 

 w^ater, sulphuric and nitric acid, coagulate it strongly, like 

 albumen." (Zoological Journal, vol. i. p. 177.) 



I am. Sir, yours, &c. 

 Nov. 1^2. 1831. G. J. 



Art. VII. Illustrations in British Zoology, By George John- 

 ston, M.D., Fellow of the Royal College of Surgeons of Edin- 

 burgh. 



1. Lucerna'ria auri'cula. 

 Sir, 

 I DO not think that the discovery of any new object or fact 

 in natural history ever gave me greater pleasure than the first 

 sight of the little creature here delineated. Its form is so 



