578 F. A. Potts, 



coiild be dimly seen tlirougli it and are indicated in Plate 15. 

 It was possible by making a slight incision in tlie mantle to draw 

 off all the larvae in the mantle cavity and then to obtain some 

 idea of the internal arrangement. 



Througli the nnder surface of the mantle (Fig. A) can be seen 

 the curved visceral mass adhering closely to the left band 

 margin of the body except where it is separated from it by an 

 opaque white structure described below as the mantle du et and 

 serving to place the mantle cavity in communication with the 

 exterior, The visceral mass itself was, in this individual, semi- 

 transparent in consequence of the spent coudition of the ovary and 

 marked externally with radiating ridges corresponding to internal 

 septa. The mantle is faintly striated longitudinally owing to the 

 presence of muscles and anteriorly to the bay contains a large 

 number of small rounded bodies which I think there is reason 

 for regarding as segmenting eggs. These give a characteristic 

 appearance to the und er surface as seen through a lens. 



The following notes refer to the appearance of the upper surface 

 when the animal has been carefully detached from its host (PI. 10 

 Fig. 3). The short peduncle is surrounded as usual by a chitinous 

 ring but this is not uniform in shape or thickness. The anterior 

 edge is much thickened and drawn out into a prominent chitinous 

 spike; the curvature of the posterior edge much less marked and 

 the Chitin thinner. A lateral view as shown in Fig. 1 clearly 

 indicates that the peduncle is not set vertically to the surface of 

 the host but really runs antero-posteriorly from host to the body of 

 the parasite. 



The bay in the left band margin is not seen from the upper 

 surface although the visceral mass and mantle duct are easily ob- 

 served through the mantle. The bodies referred to above as segment- 

 ing eggs, are absent from the upper surface of the mantle. 



The Root System. 



The Root System (PI. 16 Fig. 4) in this creature does not 

 form a compact mass as in Peltogaster or a widely ramifying System 

 affecting every organ in the body of the host like that possessed by 

 Sacculina. But the röots are mainly to be found below the ventral 

 nerve cord of the shrimp running longitudinally in the form of a 

 matted strip short branches being given oif laterall}^, some hardly 

 projecting from beneath the nerve cord, others terminating in the 



