PATERiSTAL CHARACTERS IN ECHINOID HYBRIDS. 345 
those of former }^ears. In 1909-1911 tlie hybrid larvje were 
always maternal (PI. VI , fig. 6, and Text-fig. 2), having no 
posterior ciliated epaulettes, but developiug the green pig- 
ment. In all the experiments of this year only a very low 
percentage of the eggs would fertilise with the foreign sperm. 
Perfectly healthy larvse were obtained fi'om these fertilisations, 
but in all the cultures they showed an inheritance which was 
the exact reverse of the previous years. Posterior epaulettes 
were developed, but no green pigment, showing that the 
larvae inherited their characters through the sperm (Text- 
fig. 3). 
From the cross E. miliaris ? x E. esculentus $ we 
have also obtained results which conflict with those of other 
years. Formerly the characters of the hybrid plutei were 
always maternal (PL 18, fig. 8). Posterior epaulettes were 
absent, and green pigment was present. This year we have 
had as great a difficulty to fertilise the E. miliaris eggs 
with E. esculentus sperm as with E. acutus sperm. In 
one case only did we get a good fertilisation, about 80 
per cent, of the eggs segmenting. In cultures made from 
this ci’oss some of the liybrid larva? were maternal, others 
paternal. In all other experiments the percentage of eggs 
which fertilised was twenty or less. Nevertheless, these 
1909, 1910 and 1911. 
1912. 
Posterior 
epaulettes. 
Green pig- 
ment-masses. 
Posterior 
epaulettes. 
Green pig- 
ment-masses. 
E. esculentus, $ ■) 
E. esculentus, $ ) 
+ 
0 
+ 
0 
E. miliaris, $ . ■) 
E. esculentus. ? ) 
+ 
0 
+ 
0 
E . ni i 1 i a r i s , d* • ') 
E. miliaris, :i . ) 
0 
+ 
0 
-1- 
E. esculentus, ^ •) 
E. miliaris, ? . J 
4- 
+ 
0 
