ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 719 



the Pagurid exhibits a series of actions which vary according to the 

 physiological state of the Actinian. It stimulates the Actinian in quite 

 definite ways. In contrast to such a case, the association of Actinia 

 equina and Paguristes oculatus is accidental or indifferent. 



Notes on Ceylonese Hermit-crabs.* — T. Southwell found Gancellus 

 invest igatoris Alcock, whose habitat has not been recorded, occupying a 

 small cavity in a piece of Forties arenosa. When the animal was re- 

 tracted the modified portions of the chelipeds and legs formed a remark- 

 ably perfect and inconspicuous operculum. Similarly, he found Diogenes 

 rectimanus in cavities of living coral (Goneastrea). A new species, 

 Clibanarim ivilleyi, is described and a list is given of the Anomuran 

 Fauna of Ceylon. 



Colour Change in Ligia.f — John Tait notes that specimens of Ligia 

 oceanica exposed to light in a black-painted dish retain their dark 

 appearance (due to numerous highly branched black or dark brown 

 chromatophores in the epidermis), while those exposed in a white dish 

 gradually grow lighter in colour and more transparent, so that even- 

 tually the heart can be seen beating through the integument. This 

 effect is due to a retraction of the black chromatophores. (In the 

 laterally situated lighter patches in the normal animal there are also 

 white chromatophores.) When a Ligia is blinded by having its eyes 

 painted over with lamp-black in Canada balsam it does not undergo the 

 usual change of colour on transference to a white background. The 

 stimulation of the chromatophores seems therefore to be wholly indirect, 

 the eye being the receptor organ. 



Blood-coagulation in G-ammarus.J — John Tait notes that the process 

 of blood-coagulation varies with the species of Gammarus. In G. marinas, 

 found near the upper tide-limit on the beach, cell-agglutination seems to 

 be the only visible factor in the formation of a clot ; in G. locusta, found 

 lower in the ebb, " globule " formation, associated with explosion of 

 thrombocytes, is the prominent feature. 



Light and Pigment-formation in Crenilabrus and Hippolyte.§ — 

 F. W. (ramble publishes a further instalment of the results of his experi- 

 mental study of the colour-physiology of the prawn Hippolyte varians, 

 and the wrasse, Crenilabrus rnelops. The immediate object of the 

 present series of experiments was to determine whether there was, in the 

 young fish, a sensitive stage at all comparable to that possessed by Hippo- 

 lyte. The investigator found that the colouring of the young specimens 

 of Crenilabrus melops is due in part to the blue endoskeleton, in part to 

 chromatophores. On backgrounds of seaweed they assume varied 

 coloration. On brown weed they become brown, on green weed, 

 green, and on red weed, green. In light transmitted through weeds, 

 Crenilabrus assumes a colour, the complement of that which is most 

 strongly represented in the incident light. Thus in light mainly green, 

 a brownish red colour (due largely to red pigment) develops. In light 

 mainly red, a green colour (due largely to yellow pigment) develops 



* Ceylon Marine Biol. Rep., iv. (1910) pp. 179-84 (6 figs.). 



t Proc. Physiol. Soc. (June 1910) 2 pp. J Tom. cit., 1 p. 



§ Quart. Journ. Micr. Sci., Iv. (1910) pp. 541-94 (pi.). 



