LIGIA. 91 



by Brimtz (1904), with whose results my observations 

 on Ligia oceanica are in agreement. There are four 

 kinds of excretory organs, two of which are nephrocytes, 

 either grouped or scattered ; the third is a definite 

 nephridium, or 4 kidney,' and the fourth, certain cells in 

 the hepatopancreas. 



The maxillary kidneys, or nephridia, occur in the 

 basal portion of the second pair of maxillae. They 

 consist of two parts — the saccule and labyrinth. The 

 saccule is a slightly convoluted tube, which Yejdowsky 

 considers is a remnant of the obliterated coelom. It is 

 blind at one end, and opens at the other into the labyrinth. 

 The cells forming the wall of the saccule are large and of 

 excretory nature. The labyrinth communicates with the 

 exterior by an aperture at the base of the second maxilla. 



The cephalic nephrocytes are situated at the bases of 

 the first antennae. They occur along the ventral and 

 lateral sides of the levator muscles of these appendages. 

 These cells are fairly large; the protoplasm is homo- 

 geneous and contains a number of granules. 



The branchial nephrocytes occur in the abdominal 

 region, dorsal to the attachment of the branchiae. There 

 are five pairs of groups of branchial nephrocytes. They 

 are situated in two lateral lines, each line running above 

 the points of attachment of the abdominal appendages, 

 and their outer edges reach the bases of the epimeral 

 plates. Each group borders on two segments, the first 

 group bordering on the last thoracic and first abdominal 

 segment. The nephrocytes lie on the sides of the branchio- 

 pericardial canal (PI. II., fig. 16, br. neph.). They are 

 large cells, and the cytoplasm, which is vacuolated, 

 contains many granules. Nemec considers the branchial 

 nephrocytes to be a syncytium, but the cell boundaries 

 are verv distinct, as Bruntz also noticed. 



