MODIFICATION OF THE EYE PEDUNCLES IN CYMONOMUS. 441 



wish to undertake — lie suggested that the account of the 

 facts concerning Cjmonomus should be illustrated by some 

 figures of the strange modifications shown by the eye-stalks of 

 several deep-sea Mysida3. These are illustrated in the wood- 

 cuts (see text-figures 1 to 7 and accompanying explanations). 



Fig. 3. — Boreomysis scypliops, G. 0. Sars. Adult female, 

 1900 fathoms. No ommalidia. The ocular peduncles are con- 

 verted into cup-like plates. Sars, ' Schizopoda,' pi. xxxii, fig. i. 



Yw. 4. — Petalophthalmus armifrer. Willem. Suhm. Male, 

 X 4. 2500 fathoms. No ommalidia. The ocular peduncles are 

 converted into mobile leaflets. Sars, 'Schizopoda,' pi. xxxii, 

 fiff. 1. 



Apart from these interesting cases in the Schizopoda, the 

 modification of the eyes in deep-sea decapod Crustacea is now 

 recognised as a very freqnent occurrence. The degree of 

 degeneration of the optical apparatus and accompanying 

 modification in the character of the ocular peduncles varies 

 from a simple suppression of the ophthalmic pigment and 



