298 SUMMARY OF CURRENT RESEARCHES RELATING TO 



near Dungog, New South Wales. Two of the species are new, the 

 Isopod Cubaris hehnsianus and the Amphipod Gammarus harringtonensis, 

 the former terrestrial, the latter from fresh water. The other forms are 

 the fresh-water Isopod Phreatoicus shephardi Sayce, and the terrestrial 

 Amphipod Talitrus sylvatkus Haswell. All four forms present points 

 of individual interest, and their geographical distribution is important. 



Immersion Experiments on Ligia oceanica.* — John Tait calls 

 attention to the terrestrial mode of life which is now habitual with this 

 species. Specimens placed in half sea-water survived from sixteen to 

 forty- two days. Only in one case (that of thirty-seven days' survival) 

 was there any appreciable change at death ; this consisted in the swelling 

 of one internal gill-lamella. In quarter sea-water there was survival 

 for three to fifteen days. Two of the animals showed marked oedema 

 before death. One of these, replaced in sea-water, recovered its power 

 of movement, and on the following day the oedema had subsided. Over 

 one hundred and fifty experiments were made with distilled water. After 

 the first eight or nine hours individual animals began to die, and this 

 might continue for at least thirty-six hours thereafter. QEdema is 

 common, but not invariable. There is an extraction of salts from the 

 body. The longest survival-period accurately measured was forty-four to 

 forty-five hours. The resistance in recently moulted specimens is greater 

 than with specimens that had moulted some time before. The animals 

 can live for three months in sea-water in apparent comfort, yet they 

 prefer a land habitation. There may be respiratory reasons for this. 



Moulting in Ligia.t— John Tait finds that Ligia, like other 

 Isopods, moults in two stages. First the covering of the abdomen with 

 that of the posterior three thoracic segments is exuviated. About four 

 days later the covering of the anterior region of the body is thrown off. 

 The author describes the external changes in the cuticle as it ages, and 

 the behaviour of the animal during the process of moulting. 



At the moult the cuticle splits in two main directions : (1) transverse, 

 between the fourth and fifth (free) thoracic segments ; (2) longitudinal, 

 at the coxotergal junctions of (free) thoracic segments 2 to 7, there 

 being no coxotergal split in segment 1. Coxotergal splitting is an 

 arthrostracan, if not a peracaridan, feature. 



Specimens that have fasted for many weeks in sea-water may still 

 moult normally. It follows that onset of the moult is determined by 

 an underlying cyclic change, not, as Reaumur suggested, by simple 

 growth of the animal. A second moult during the period of fast was 

 not observed. 



Limb-flexures and Limb-taxis on Peracarida.| — John Tait has 

 studied in a very interesting way the question of limb-flexion as met 

 with in Peracarid Crustaceans. He is led on to a discussion of the 



• Proc. Roy. Soc. Edinburgh, xxxvii. (1917) pp. 50-8. 

 + Proc. Eoy. Soc. Edinburgh, xxxvii. (1917) pp. 59-68. 

 X Proc. Roy. Soc. Edinburgh, xxxvii. (1917) pp. 69-94. 



