Mr. R. M^ Andrew on Mr. Jeffreys' s last Dredging Report. 361 



am acquainted with. In the former case they were littoral, in 

 the latter on a red Fucus obtained from a depth of from 10 to 

 20 fathoms. 



4. '' The colour of specimens from the greatest depths is not 

 less vivid than from shallow water," &c. This statement 

 would imply either that no rays of light are intercepted or de- 

 flected in their passage through water (in which case we ought 

 to be able to see objects as well through this medium as through 

 air) — or that light has no effect upon colour, which I may ven- 

 ture to say is not the case. I have no reason to suppose that 

 colour is affected by depth, except in relation to the supply of 

 light, or that the effect of light is appreciable except where 

 the colour is superficial. The colour of our blood may be 

 independent of the action of light, though not so that of our 

 complexions. It should be observed that in some of the ex- 

 amples mentioned by Mr. Jeffreys the colouring-matter per- 

 meates the substance of the shell ; and with respect to Venus 

 ovata I must add that my experience is at variance with his 

 statement, which I therefore presume must be founded upon 

 some exceptional case. There are in the national collection 

 specimens, not selected, of Venus ovata and V. striatula^ pro- 

 cured by me from a depth of 80 fathoms and upwards, which 

 will be found to be of a chalky consistency and almost desti- 

 tute of colom*. 



The effect of light in heightening the superficial colour, 

 particularly the brighter hues of shells, is evident on comparing 

 together specimens of the same species from different latitudes. 

 Venus ovataj V. verrucosa^ V. ca^ina^ all the British species of 

 Tapes^ Circe minima^ and many others have much more colour 

 in the latitude of the Mediterranean than in our seas, which 

 is naturally attributable to exposure to a more intense light. 



It is a remark of Forbes, which my own observation has 

 confirmed, that the species of Mollusca peculiar to great depths 

 are generally void of colour. 



Of the remaining propositions I will only remark upon 

 7. " Exotic and oceanic shells are carried northward by 

 westerly winds, and not directly by the Gulf-stream, which 

 does not reach our coasts," that I do not see how the distribu- 

 tion of Mollusca inhabiting the bottom of the sea can be 

 affected by winds, from the direct influence of which they are 

 so effectually removed. With respect to animals frequenting 

 the surface of the ocean, such as lanthina and Velella^ which 

 occasionally appear on our coasts in considerable numbers 

 after a prevalence of westerly or south-westerly winds, they 

 are temporary visitors, and have not succeeded in establishing 

 themselves permanently in om* seas. 



