PLATE X. 



PLEUROSIGMA ANGULATUM. 



(Magnified 4900 diams. 



From a Pnoto-Micrograph by Dr. R. Zeiss taken with the 2 m/m. Apochromatic Objective 

 N. A. 1.30 and projection eyepiece 4. 



rollotjpe Ptg. Co., 282 High Holborn, W.C. 



