Experimentally Fused Larva oj Echinoderms, etc. 



109 



satory growth of other parts of the skeleton were observed in varying 

 degrees of complexity in all or nearly all the fused larvae. 



The two plutei of figure 6 are fused more completely together than the 

 preceding pair of plutei. The two larvae are perfect and the parts are 



Left d.a.r. - 



typical and independent, except the body wall, which is common to both. 

 In the right or A pluteus each of the skeletal parts is differentiated and 

 normal. In the left or B pluteus the ventral body rods are incomplete in 



d.v.c.--- 



Fig. 6. 



so far as they do not possess their aboral bifurcated branches, and one 

 of the ventral arm rods is abbreviated. The B pluteus in this fusion is 

 incomplete, not with respect to the dorsal rods, as in the previous example, 

 but in the aboral branches of the ventral body rods. 



