PLATE CXLIX. 



Fig. 1 . Sylon challengeri, attached to Spirontocaris spinus, a part of the right side of 

 the Shrimp having been taken away; x, the injured part at the surface of the 

 sac ; I., II. , III., IV., and V., the first to the fifth pleopods of the left side of 

 the Shrimp ; Va, the fifth pleopod of the right side. Magnified 1 3 diameters. 



,, 2. Sylon challengeri, seen from below, with a part of the wall of the host 

 attached ; e, the ovary of the parasite. Magnified 1 2 diameters. 



„ 3. Sylon challengeri, front view; x, the injured part at the surface. Magnified 12 

 diameters. 



,, 4. Sylon schneideri, front view ; a, openings leading into the mantle-cavity ; B, 

 transverse section of Hippolyte pusiola. Magnified 12 diameters. 



,, 5. Sylon schneideri, seen from the side, the lateral parts of the exoskeleton of the 

 second and third abdominal segment of the Hippolyte being taken away ; 

 a and B as in fig. 4 ; II.-IV., second to fourth pleopod. Magnified 

 12 diameters. 





