F. A. POTTS 



PLATE 1 



Fig. 1 . Thompsonia on Synalpheus brucei. Young external sacs on the abdominal and thoracic 

 appendages, x 3. 



Fig. 2. The same at a later stage. The external sacs now contain Cypris larvae which are roughly 

 indicated within, x 3. 



Fig. 3. Thompsonia on Thalamita prymna. To show the very large number of external sacs occurring 

 on this specimen. Natural size. 



Fig. 4. Thompsonia on Actasa ruppellii. External sacs pear-shaped, x 2. 



The first three specimens figured are from Murray Island, the fourth from South Africa. 



