74 L. A. BORRADAILE. 



ii. The Alimentary Canal. 



A. The Fore-gut'. (PI. III. figs. A — E). The short, wide oesophagus presents no 

 feature of special interest. In correspondence with the compression of the fore-part of the 

 cephalothorax mentioned above", the Maw or "Stomach" is narrow and elongated. The 

 hinder or "pyloric" division is nearly horizontal, and is sundered from the anterior "cardiac" 

 portion by the usual deep hollow on the dorsal surface of the stomach. The cardiac sac 

 is narrow, rounded in front and somewhat flattened above. The walls of its thin fore-part 

 show on each side the thickened " cardiac disk " found in other Pagurinea (8, PI. III.). 

 Internally, this disk bears seven or eight tufts of long hairs, placed on pointed prominences 

 arranged along its lower edge. 



The gastric mill is strong, no doubt in connection with the nature of the food, which 

 is chiefly vegetable, and often consists of such tough substances as the fruits of the screw- 

 pine (Pandanus). In the viesocardiac ossicle (1, PL III.), the most prominent part is a strong 

 band acro.ss the roof of the cardiac divi-sion of the stomach, bent in the form of a bow, 

 and lying with the hollowed side forward ; its ends are broadened. In front of this is a 

 thinner portion, which merges gradually into the thin wall of the fore-part of the stomach. 

 Behind the ossicle the roof of the stomach falls away into the hollow between the two 

 divisions. The rounded hinder edge of the bow projects somewhat over this gap, and 

 overhangs a wide, triangular process from its own underside, which forms part of the hind 

 wall of the cardiac portion — the anterior wall of the hollow. The apex of this triangular 

 plate, by which it joins the fore end of the urocardiac ossicle, is not pointed, but ends 

 in two rounded lobes, of a bright white colour and strongly calcified. The pterocardiac 

 ossicles (2, PI. III.) are triangular or rather three-lobed structures in the side wall of the 

 cardiac division, at the outer ends of the bow of the mesocardiac. One lobe is directed 

 outwards, one inwards, and one downwards. Between the outward and the inward lobes 

 lies that edge of the ossicle which articulates with the broadened outer end of the meso- 

 cardiac bow. The zygocardiac ossicles (3, PI. III.^) also lie in the side walls of the stomach, 

 but behind the mesocardiac. Each is a roughly diamond-shaped plate of large size, placed 

 so that its longer diagonal runs tore and aft. There are thus an anterior and a hinder 

 angle. The latter is directed somewhat downwards, so that, of the two edges of the 

 diauiond which are uppermost, the hinder slopes downwards, while the more anterior is 

 almost horizontal. This latter edge is much thickened and curled inwards, towards the 

 cavity of the stomach. The other edges are also thickened, though not to the same extent. 

 The lateral tooth (3.5, PI. III.), borne internally by the zygocardiac ossicle of each side, is 

 strong, and bears a series of transverse ridges which grow smaller from before backwards. 

 The first three or four of these are much larger than the hinder ones, and are set 

 farther apart. 



' lu writing tlie following account of the fore-gut and the three Minikoi species. Thus the total material available 



its armature in Coenobita, I have been much helped by has reference to at least five out of the six species of the 



Mocquard's work on these organs of the Decapoda [Ann. Sci. genus. 

 Nat. (6) Zool. XVI. i. (188b)], and especially by the numerous =' p. 70. 



allusions to this genus scattered through his section on the '■' This ossicle is so placed that it overhangs and presents 

 Pagurinea. Though he figures no Coenobita, Mocquard had one face downwards and an edge (the horizontal one) out- 

 dissected three species — C. compressus, C. spiiwsus, and a third wards. Its shape is therefore not properly seen in a full side 

 whose name he did not know. The present account is based view and cannot be made out in fig. A, PI. III. but may be 

 on the information given by Mocquard and on dissections of seen in the ventral view (tig. C). 



