PLATE III. 



Fig. 



1. Tetrastemma Bobertiance, n. s. 



2. Amphiporus spectabilis, De Quatrefages. 



3. Tetrastemma vermicula, De Quatref., with the body slightly turned over in the middle. 



4. „ dor salts, Abild. A very large and fine specimen. 



5. Head of Tetrastemma Candida, var. ? From deep water, St. Andrews. 



6. Nemertes Neesii, (Erst., in one of its usual spiral conditions. 



7. Dorsal aspect of the anterior region of Amphiporus spectabilis, De Quatref. Enlarged under 



a lens. 



8. Ventral surface of the same region in A. spectabilis. Enlarged under a lens. 



