147 
that the breeding season of Brissopsis began that year somewhat 
later than in 1918 —). There cannot be the slightest doubt that 
we have then here really the larva of Brissopsis lyrifera. 
The larva is easily distinguished already in its quite young 
stages from the Echinocardium larva by the postoral, postero- 
dorsal and posterior rods being fenestrated only in the outer part, 
their basal part remaining unfenestrated; in this character it agrees 
with the larva of Spatangiis purpiireus and I cannot say at pre¬ 
sent how to distinguish these two larvæ in the younger stages. 
The fully formed larva (Fig. 2) is very distinctly characterized by 
having no poster o-lateral arms, only a pair of small ear- 
10* 
