\ 



PLATE II L 



1. General view of a full-grown specimen of Balanoglossus Kowalevskii, as seen lying in a dish, from the dorsal 



side. ^. 



2. Magnified portion of the anterior part of another specimen of the same age, seen from the dorsal side. 



3. Speci 



very much younger, but older than the one figured on PI. II., f. 8, seen in profile previous to the 

 formation of the liver and of the genital organs, 35 tnm ' in length. 



4. Magnified portion of anterior part of same (Fig. 3). seen from the ventral side. 



5. Anal extremity of specimen of Fig. 1. 



6. Anterior extremity of the proboscis, to show terminal opening. 



7. Anterior extremity of another specimen, about the age of Fig. 3, still showing traces of the eye-specks. 



8. Posterior extremity of the proboscis, to show the ventral opening contracted. 



9. Posterior extremity of the proboscis of another specimen, showing the long ventral opening. 



10. Portion of anal extremity of the body, seen from the ventral side. 



11. Portion of ventral part of the body immediately behind the termination of the gills, covered by glands 



secreting mucus. 



12. Portion of the dorsal part of the body a short distance behind the gills, covered by glands secreting mucus. 



1 3. Part of the anterior portion of the sides of the body in which eggs are developed. 



14. Part of the anal extremity of the body. 



15. Portion of body showing the long narrow folds forming the so-called liver. 



