112 A HISTORY OF EECENT CEUSTACEA 



legs. In Dorippe, Leucosia, and Ranina, the lower border 

 of the trunk closely coheres with the epimera (compare 

 Milne-Edwards, vol. 2, p. 193). In the first the anterior 

 apertures, in which the first joints of the third maxillipeds 

 work, are remote from the base of the chelipeds ; but in 

 the following they are altogether wanting ; so that these 

 have only one path on each side by which the water reaches 

 the branchiae, and one by which it is withdrawn. The 

 hinder ducts in Ranina are broader than in other families 

 and amplified by lateral apophyses, but otherwise in Portu- 

 nus and Qra/psus they are in the same place. The water 

 appears to enter the branchial cavity by the anterior aper- 

 tures, and to issue by the hinder ones, and not to have a 

 diverse or in Ranina and Leucosia a contrary motion 

 (compare Milne-Edwards, vol. 1, p. 88, vol. 2, p. 194). 

 In the anterior part there is a force, namely the movement 

 of the maxillipeds, by which the water is brought in ; that 

 being expelled behind, follows the movements of the body ; 

 the apertures beside the base of the chelipeds and the 

 branchial appendages of the maxillipeds are ciliated on 

 the margin, and by these cilia alien bodies are kept away 

 from the branchiae, when water is brought to them from 

 in front, whereas [they would be] of no use but a hindrance 

 to breathing, were the water brought from behind.' 



Fritz Muller refers to the statement made by Milne- 

 Edwards about the breathing arrangements of Ranina, but 

 does not mention de Haan's contrary opinion. Fritz Muller 

 himself unfortunately had not had an opportunity of per- 

 sonally investigating the question. Judging from Milne- 

 Edwards' figure of Ranina dentata, it would appear to 

 have an arrangement of the pterygostomian regions not 

 unlike that already described in the genus Sesarma, by 

 which the crab when on dry laud is enabled for a long 

 time to go on breathing the same small stock of sea-water. 

 Such an arrangement would undoubtedly be convenient 

 for the Ranina, if the story be true that it has a decided 

 propensity for climbing on to the roofs of houses. Milne- 

 Edwards attributes this story to Eumphius, but nothing 

 of the kind appears to be included in that author's account 



