Mycetoniorpha. 



579 



ventral musculature of the host. They sonietimes fork and end in 

 clubshaped swellings containing a crowded niass of nuclei. Posteriorly 

 they can be traced for about the length of a segnient and a half 

 in the host and anterioi'ly for a lesser distance. They are probably 

 white in coloiir and in their general histological character they 

 resemble those of SaccuUna and Peltogaster. Under a thick (niticle 

 lies an iriegnlar epitheliuni and the inferior is occnpied by ninch 

 vacuolated tissue with very small nuclei. At the junction of the roots 

 in the neighbourhood of the peduncle a large and distinct laciina is 

 found and the further course of this is described below. 



It now remains to trace the anatomy of the animal as revealed 

 in sections: these were cut transverselj^ as shown in P^ig. A. 



Fig. B. Transverse Section showing the internal aperture of 



the mantle dnct. 



r root sj'stera, hs chitinons exoskeleton of host, m mantle, 



vac. m. d vacuolated tissue of mantle duct, Cijp Cypris larva. 



Other abbreviations as in Fig. A. 



Fig. A. 



Diagram of the visceral mass show- 

 ing its relation to the mantle cavity. 

 Seen from the under surface. v. m 

 visceral mass, tu. c mantle cavity, 

 m. d mantle duct, i. a internal and 

 e. a external aperture of mantle duct, 

 l. m lateral mesentery. 



The longitudinal shading indicates 



the musculature of the mantle and 



the black spots the developing eggs 



vi'ithin it. 



The red lines represent the vertical 



planes in which the figures cor- 



lesponding to the lettering were 



cut. 



Fig. ( '. Transverse section showing the external aperture of the 



mantle duct. div diverticulnm of mantle cavity filled with 



Cypris larvae. Other abbreviations as in Fig. A and B. 



