PATEENAL CHARACTERS IX ECHINOID HYBKIDS. 341 
The following is a brief description ot the late larvaa of the 
three pure forms and of the hybrid crosses. 
Text-fig. 2. 
Miliaris. Acutas. 
MjxAo'. AjxMc/. 
Diagram to show the inheritance of the late larval characters in 
hybrids between E. miliaris and E. acntus during 1909-11. 
(//• p. Green pigment-mass. p.cU.ep. Posterior ciliated epaulette. 
The two upper figiu'es repi’esent the unhybridised larvae. 
'I’he plnteiis of E. esculentus reaches the 8-armed 
stage at about a fortnight after fertilisation. The age of a 
pluteus is, however, seldom a good indication of its stage of 
development, as the rate of growth in different cultures 
