NEPHRIDIA AND BODY-CAVITY OF DECAPOD CPvUSTACEA. 405 



been so fully and accurately described for this and other 

 species by Grobben (No. 10), Marchal (No. 17), and Weldon 

 (No. 20). The only point upon which there appears to be a 

 division of opinion is as to the nature of the most internal 

 layer of the tube {cut.), which Grobben considers to be a 

 cuticle pierced by fine pores, whilst Marchal regards it as 

 made up of rows of minute vesicles, which subsequently en- 

 large and break away from the cells. Without expressing 

 an opinion as to the latter point, I can say that Marchal's 

 figures (No. 17), especially his fig. 8, pi. v, represent much 

 more nearly the appearance of this layer, as I have observed 

 it, than the figures given by Grobben (No. 10). 



The condition of the green gland represented in fig. 1 occurs, 

 as I have stated, in larvse which are a few days old. At the 

 time of hatching, however, a more primitive condition is 

 found, for when this event takes place the gland is entirely 

 without a lumen, although the ureter and external opening 

 are present. A transverse section through it at this stage 

 is represented in fig. 2. The gland has the same general 

 shape as in the later stage, and the end-sac [e. s.) and bladder 

 {bl.) are easily distinguished. They consist, however, of solid 

 masses of cells, in which as yet no cavity has appeared. A 

 few hours after the larva is hatched the cells begin to separate, 

 and so give rise to the lumen of the gland. A transverse sec- 

 tion at this time is shown in fig. 3. 



The striation of the protoplasm of the bladder can be indis- 

 tinctly seen in these early stages, but from the appearance of 

 the gland I should not judge that it was yet functional. 



The later development of the green gland consists chiefly in 

 the enlargement of the bladder. The latter commences to 

 grow in the region indicated by the letter E in fig. 1. At the 

 end of a week after hatching its enlargement has already 

 passed out of the basal joint of the second antenna, and by the 

 end of a fortnight it has grown inwards beneath the circum- 

 oesophageal nerve-commissure as far as the mid-ventral line. 

 A still later stage is represented in fig. 4. Here the bladder 

 has commenced to grow in a dorsal direction, anterior to the 



