EUPAGURITS . 515 



caeca gives no clue to their function. The cells are long 

 and columnar, with small oval nuclei situated near their 

 base. They have a striated border similar to but narrower 

 than that of the mid-gut. The cavity is occluded by the 

 much folded walls. 



The histology of the digestive gland differs somewhat 

 from that described by Pearson in Cancer. The so-called 

 "fat cells" are never scattered round the lumen, but 

 bulge out from one point only at a time (fig. 23). It 

 seems doubtful whether the division into "fat" and 

 "ferment" cells can be justified, and whether the fat 

 cells are not to be considered only as ferment cells engaged 

 in excretion. These cells have a very distinctly striated 

 border (fig. 24). Small deeply-staining cells are found 

 between the larger ones. They probably give rise to the 

 ferment cells. The nuclei of the " ferment " cells are to 

 be found two-thirds of the way from the periphery, those 

 of the "fat" cells at their extreme base, nearly all the 

 cell being filled by the huge oil globule. 



BLOOD VASCULAR SYSTEM (Pis. Ill and IV). 



With the exception of the portion of the blood 

 system which relates to the abdomen, the course of the 

 blood, both arterial and venous, is that of a normal 

 Decapod Crustacean. As in the crayfish or the crab, the 

 pure blood from the gills passes to the pericardium and 

 is driven by the heart through definite blood-channels to 

 the various parts of the body, whence it returns for 

 aeration by means of irregular sinuses to the gills. 



The Heart (fig. 28) lies in a space, the pericardium, 

 situated directly under the cardiac part of the 

 carapace. It appears pentagonal in shape from above 

 and rectangular from the side, though not so markedly 



