38 SUMMARY OF CURRENT RESEARCHES RELATING TO 



arc larger and stronger than the males, the furmor show the more 

 brilliant coloration. Young animals are often differently coloured to 

 the adults, their colours are generally more like those of the adult 

 female. The young of several species that are most dissimilar in 

 their colours when adult, arc often hardly distinguishable in this 

 respect. 



Sense of Colour and of Brightness in Animals.* — V. Graber has 

 investigated the sense of colour and of illumination in animals. To 

 decide whether animals had a sense of light or of colour he placed 

 them in a box so arranged that qualitative or quantitative rays fell on 

 one or other of its two divisions, which communicated with one 

 another. Five mammals, seven birds, two reptiles, three amphibians, 

 two fishes, three mollusca, twenty-seven insects, two spiders, and two 

 worms were experimented with. It was found that the sense of 

 colour as well as of the power of perceiving light was much more 

 mdely distributed among animals than has been generally supposed. 

 The variations in the sense of colour in various animals is very great, 

 but a much greater number of observations must be made before a 

 definite solution of the problem can be obtained. 



Influence of "Wave-currents on Fauna of Shallow Seas.f — 

 A. E. Hunt points out that the power of submarine wave-action, 

 hitherto neglected by natiu-alists, is sometimes considerable at depths 

 of 40 fathoms and more, and that the fauna is influenced thereby 

 to an extent scarcely possible to be overrated. 



He specially dwells on the case of animals, chiefly Mollusca and 

 Crustacea, living on, or in, a sandy or muddy bottom outside the tide 

 marks. Such animals as seek safety in their capacity for maintaining 

 themselves to a greater or less extent below the surface of such a bottom, 

 do so either by their power to burrow rapidly, as Paammobia tellinella, 

 or by the power of retaining a safe position when once secured, as in 

 Cardium and the Veneridse, which are provided with special mooring 

 apparatus in their roughened exteriors and spinous processes. The 

 group of animals that live on the sea bottom on sand or mud, exhibit 

 great variety of special adaptations of structure to resist or evade wave 

 action, and examples are adduced from the Gasteropoda (Ajyorrhais, 

 Murex, Pteroceras, and Strombus), Echinodermata (Asterias and Ante- 

 don), Crustacea, and fishes. 



In conclusion, the author shows how under the influence of wave- 

 currents, the variation of species may be promoted and their local 

 extinction brought about. 



Claus' Elementary Text-book of Zoology.^ — The reputation of the 

 original work and its author is deservedly great, and Mr. Sedgwick 



* Giaber, V., ' Grundlinien zur Erforschung des Ilelligkoits und Farbcn- 

 sinnes der Tiere,' 8vo, Leipzig, 1884, viii. and 322 pp. See Naturforscher, xvii. 

 (188-1) p. 473. 



t Joum. Linn. Soc. Lond. (Zool.) xviii. (1884) pp.-262-74. 



J Claus, C, ' Elementary Text-book of Zoology. General part and special part : 

 Protozoa to Insecta. Translated and edited by Adam Sedgwick, M.A., with the 

 assistance of F. G. Heathcote, B.A.,' 615 pp. and 491 fig.5. 8vo, London (W. Swan 

 Sonuenscheiu & Co.) 1884. 



