Mateb. — Staurocephalus gregaricus. 



PLATE 3. 



Fig. 18. Larva of Staurocephalus gregaricus, nnv. sp., 10 days old. 



Fig. 19. Dorsal view of a young worm 16 days old. The animal now ceases to 



swim through the water, but will readily burrow beneath the surface 



of sand upon the bottom of the aquarium. Length 0.8 mm. 

 Fig. 20. Ventral view of the head end of a young worm 16 days old, showing the 



"jaws" of the oesophagus. 

 Fig. 21. Dorsal view of a worm 2(3 days old. Length 1.2 mm. 

 Fig. 22. Side view of a worm 2G days old, showing the " jaws " in the oesophagus. 



(m) mouth. 

 Fig. 23. Side view of the posterior segment of a worm 20 days old, showing cirri. 

 Fig. 24. Dorsal view of a worm 34 days old, showing the beginnings of the mature 



coloration immediately back of the eyes. Length 1.5 mm. 

 Fig. 25. Seta from a worm 26 days old. 

 Fig. 26. Dorsal view of the dorsal "jaws" from the oesophagus of a worm 26 



days old. 

 Fig. 27. Side view of the dorsal " jaws " from the oesophagus of a worm 20 days 



old. 



