434 G. WYNHOFF. 



Locality: Abundant everywhere in Plymouth Sound; Eame-Eddystone 

 Grounds, and between weeds in Whitsand Bay. 



I found several varieties of the species in dredgings ; of these 

 0. dorsalis var. marmorata was the most common ; I found it every- 

 where in Plymouth Sound, at Whitsand Bay and in the Piame-Eddy- 

 stone dredgings. From the last spot, however, I several times collected 

 the variety viridis (Burger, Monogr., PI, III, Figs. 34 and 34a), and on 

 one occasion a single specimen of var. cincta (Bilrger, Monogr., PL III, 

 Fig. 27). 



Geographical distribution : Atlantic Ocean, with the Baltic, North 

 Sea, the Channel and the Mediterranean. 



Utrecht, September, 1911. 



