28 NOTES ON BOPYRUS SQUILLAEUM. 



The existence of Bopyruit has been known for some time, but not 

 properly understood; for in the year 1772 Mons. de Bondaroy, a French 

 naturalist, published a memoir on Bopynis squillarum disproving the 

 old fallacy entertained by fishermen on the coasts of France that 

 Boptjri were the young of soles or other fiat fish, which took shelter 

 under the shell of the prawn to protect them in their early stages of 

 growth — an idea held even by some scientific men at that period. In 

 the year 1837 Ratbke made some interesting observations upon 

 Bopynis, showing from an examination of a number of specimens that 

 they usually infested the feuiale prawn only, for out of several hundreds 

 infested the male prawn was free. It appears to me that we have not 

 to go far to seek an explanation of this. The ova of the prawn afford 

 a "fitting environment" for the young Bopyri, which need to be 

 sheltered in their early stages preparatory to their entrance under the 

 carapace of their host. It is, therefore, not too much to say that in 

 this instance their very existence is dependent on the fertility of the 

 prawn. 



Dr. Fritz Miiller made, in the year 1861, a very remarkable 

 observation on a member of the Bopi/ridce, which he communicated to 

 the authors of the •' British Sessile-Eyed Crustacea." He says : " One 

 of the most interesting animals of this family is a Bopynis living on 

 Payunis (a genus of the hermit crab), in which the dorsal surface of 

 the parasite is directed towards the Pagunis. (He therefore named it 

 Biipyru^ resiqnnatus.)" The origm of this curious mode of attachment 

 is the following : — The larva of Bopynis affixes itself to SaccuUria pur- 

 purea (another parasite of the non-segmented suctorial order of 

 crustaceans (Rhizocephala) living on the same Payunts), and takes its 

 nourishment from the roots of the parasite. After the death of the 

 SaccuUna. to whose central surface the Bopynis was fixed, the latter 

 probably cannot change its position, and remains with its dorsal surface 

 facing the Payunis. 



Finally, in briefly contrasting together the two adult animals, the 

 host Pahcmon and its parasite Bopynis, we have the symmetrical, 

 compact, segmented body of the one, and the unsymmetrical body of 

 loose consistence of the other — -the cephalothorax with its stout 

 rostrum and compound eyes gives place to a mere extension of the 

 body of the other — the complicated mouth of the one is represented by 

 a mere sucking apparatus in the other — the long and sensitive 

 antennse of the one are represented by mere aborted extensions in 

 the other ; the ramifying branchiae of the one give place to rudi- 

 mentary organs in the other ; the long, slender, and graceful walking 

 and swimming feet of the one are represented by dwarfed limbs in the 

 other; but, as a compensation, and the only one of the greatest import- 

 ance to the parasite, the hands are both strong and numerous to aid it 

 in grasping and holding on. Bopynis exemj^lifies in an eminent degree 

 a retrogressive phase of the theory of evolution. PaUemm, on the 

 contrary, illustrates a progressive phase of that great theory. 



If I have at all succeeded in enabling the members to gain a 



