90 



L. A. BORRADAILE. 



outer shell, prolonged into a stalk which adheres to the hair. The ripe egg is ellipsoidal, 

 and measures, when preserved in spirit, 7".5 mm. by 7 mm. in C. perlatus, and in C. rugosus 

 rather less. It is thus a little smaller than that of Birgus\ In two species at least 

 (C rugosus and C. perlatus) the young are hatched as zoaea larvae '' of a type much re- 

 sembling those of other Pagurinea" and washed off into the sea. They are not swept out 

 in the respiratory current in the manner described by Bate* for Eupagurus nor is it 

 necessary for the liemale to issue from her shell, though she may do so if kept under 

 water too long in a state of captivity. It is possible, though perhaps not very likely, that 

 the habits of some of the other species, especially those which live at greater distances 

 from the water, may have led to their young being hatched in a later stage ^ as is said 

 to be the case with some land crabs*. A zoaea which seemed identical with that of C rugosus 

 was taken at night with the tow-net in the lagoon at Minikoi. 



The embryonic skin, which encloses the Decapod zoaea before hatching, and is retained 

 for a varying period in different forms, is here lost very shortly after leaving the egg. It 

 is of simple form and much resembles that found by Sars in other Pagurine zoaeas, though 

 I have not been able to discover any feathering on the processes of the glove-like structure 

 which encloses the telson and its spines. The larva (fig. 21) is rather smaller than that 



of Birgus'' (the length is, in C. perlatus, 3 mm. 

 and in C rugosus 2"5 mm., as against 3'5 mm. 

 in Birgus), which it otherwise very closely re- 

 sembles in all but a few points of detail. The 

 carapace has a curved, pointed rostrum of moderate 

 length. The hinder edge is hollowed, and at each 

 side a rounded side-lobe replaces the spine usually 

 found here. The abdomen consists of five seg- 

 ments and an end part, which shows indications 

 of its coming division to form the sixth segment 

 and telson*. The telson {a, fig. 21) has the usual 

 fan shape with a rather deep median notch. On 

 each side of the notch are five bristles, increasing 

 in length from the first to the fourth, which is 

 longer than the fifth. These bristles are feathered. 

 The outer angle is provided with a stout tooth. 

 None of the other abdominal segments are armed, 

 save the fifth, which has a single strong spine on 

 each side at the hind end. There are eight pairs 

 of limbs, including a rudimentary pair of third ma.villipeds. These limbs are almost exactly 

 like those of the first zoaea stage of Birgus^, except for the mandible (6, fig. 21), which has 



Fig. 21. Zoaea of Coenohita perlatus. a. Telson enlarged 

 h. Mandible enlarged. 



1 Borradaile, loc, cit. 



2 Borradaile, P. Z. S., 1899, p. 937. 



' G. 0. Sars, Arch. Math, og Naturvid., xiii. p. 133 

 (1839). 



* Bate, quoted by Stebbing "Crustacea," p. 164, London, 

 1893. 



' C. cbjpeatus a few mm. long are found in the jungle in 

 Minikoi in sea shells. For C. dioonnes, see below, p. 91. 



* Gecarcinus sp. Westwood, Fhil. Trans., 1835. 

 " Borradaile, Willey's " Zool. Eesults," loc. cit. 



* These indications are not altogether wanting in Birgus, 

 so far as can be seeu in the ill-preserved material from the 

 Pacific at my disposal. 



' For figures of these see Borradaile, Willey's " Zool. 

 Results," loc. cit. 



