Emhryoloijy o/Opliiocoma echinata, Agassiz. 459 



by j\IetschnikofFand in starfisli larva3 by Brooks and Field, I 

 find that soon after their Ibrniation the two anterior pouches 

 both communicate with tlie exterior through pore-canals 

 Avhich open on the dorsal surface of the larva. 



At about the time of the formation of the pore-canals or a 



Fiff. 3. 



little before, the larval mouth breaks through on the ventral 

 surface and there is formed the perfect bilaterally symmetrical 

 larva shown in fig. 3, which is the optical section of a larva 



rpc 



l^ing on its dorsal surface, the outlines having been made 

 with a camera lucida. 



The pore-canals are not, as Bury describes, intracellular 



