122 



H. H. NEWMAN. 



advanced of the Brachiolarice, and would without doubt have 

 developed the mouth and other oral structures of the adult from 

 the right-hand side of the larva. If this type of symmetry 



/77. S. 



int. 



FIG. 14. Brachiolaria larva seen from the left side. The primitive tentacles of 

 the prospective adult are numbered i, 2, 3, 4, 5. Other lettered structures the 

 same as in previous legends. 



FIG. 15. Posterior portion of another Brachiolaria larva, showing another stage 

 in the formation of the prospective adult. 



FIG. 16. Ventral external view of the preoral lobe of Brachiolaria shown in 

 Fig. 14. The median brachium (m.br.) has a median sucker (m.s.) with six papillae 

 (/>). There are two short lateral brachia (l.b.) each with a poorly developed lateral 

 sucker (l.s.). Between the lateral suckers is a median thickening (m.th.) which may 

 be another sucker. 



reversal takes place sometimes in nature, as it doubtless does, 

 there appears to be nothing about the anatomy of the radially 

 symmetrical adult to indicate whether it has been derived from a 

 larva with the normal or one with the reversed asymmetry. 



In attempting to account for repeated failures to rear these 

 asteroid larvae through the period of metamorphosis, it has 

 occurred to me that in nature there doubtless takes place a 

 radical change in the dietary of the young individuals, which up 

 to metamorphosis had been herbivorous, feeding largely upon 

 diatoms, and that after metamorphosis they change to a car- 

 nivorous diet; for the adult is strictly carnivorous. Hence 



