Echinoderm Hybridization. 



121 



fertilization, I obtained segmentation, but I am not prepared to say 

 whether the segmentation was parthenogenetically produced or was the 

 result of fertilization. 



We have sufficient evidence, I believe, to warrant the belief that 

 each egg requires a certain definite environment for fertilization by 

 foreign sperm. That necessary environment has been determined only 

 for the sea-urchin egg. 



TABLE OF SUCCESSFUL ECHINODERM CROSS-FERTILIZATIONS. 



Arbacia punctulata 9 



X Mellita pentapora 6' (Tennent) . 

 X Moira atroposS" (Tennent). 



Arbacia pustulosa 9 



X Dorocidarisd' (Vernon). 



X Echinocardium d^ (Stassano). 



X Echinus d" (Driesch, Stassano, 



Vernon) . 

 X Sphwrechinus d (Driesch, Hert- 



wig, Stassano). 

 X Strongylocenirotus c? (Driesch, 



Hertwig, Vernon). 



Asteracanthion berylinus 9 



X Asteracanthion pallidusd (Agas- 

 siz) . 



Asterias forbesii 9 



X Arbacia piistulatad (Morgan). 



Dorocidaris 9 



X Strongylocenirotus d (Vernon). 



Echinocardium cordattt.m 9 



X Arbacia pustulosa d (Stassano, 



Vernon) . 

 X Echinus d (Vernon). 

 X SphcBrechinus c? (Stassano, Ver- 

 non). 

 X Strongylocenirotus d (Vernon). 



Echinocarditmt mediterraneum 9 

 X Echimisd (Vernon). 

 X Sphcerechinus d (Vernon). 

 X Strongylocenirotus d (Vernon). 



Echinus acutiis 9 



X Arbacia (f (Vernon). 



X Sphcerechinusd (Vernon). 



Echinus niicrotuberculaius 9 



X Arbacia d (Driesch, Vernon). 



X Echinocardium d (Stassano, Ver- 

 non). 



X Echinus acutusd (Vernon). 



X Strongylocenirotus c? (Driesch, 

 Hertwig, Vernon). 



X SphcBrechinus d (Driesch, Mor- 

 gan, Vernon). 



Hipponoe 9 ( = Tripneustes) . 

 X Cidarisd (Tennent). 

 X Ophiocomad (Tennent). 

 X Peniaceros <d (Tennent). 

 X Toxopneiistesd (Tennent). 



Mellita 9 



X Moira d (Tennent). 



Moira 9 



X Arbacia d (Tennent). 

 X Mellita d (Tennent). 

 X Toxopneusies d (Tennent). 



P sammechinus miliaris 9 



X Asterias rtibens d (Giard). 



Psammechinus (pulchellus) 9 

 X Spatangusd (Kohler). 

 X SphcBrechinus d (Kohler). 

 X Strongylocenirotus d (Kohler). 



Spatangus 9 



X Strongylocenirotus d (Kohler). 

 X Psammechinus d (Kohler). 



SphcBrechinus 9 



X Echinus J" (Driesch, Hertwig, 

 Morgan, Vernon). 



X Psammechinus d (Stassano). 



X Strongylocenirotus d (Driesch, 

 Hertwig, Marion, Morgan, 

 Steinbriick, Vernon). 



X Antedond (Godlewski). 



Strongylocentrotits lividus 9 



X Arbaciad (Driesch, Vernon). 

 X Dorocidarisd (Kohler, Vernon). 

 X Echinus d (Driesch, Vernon). 

 X P sammechinus d (Kohler). 

 X Spatangus d (Kohler). 

 X Sphcerechinus d (Hertwig, Koh- 

 ler, Morgan, Vernon). 



Strongylocenirotus purpuratus 9 



X Asterias capiiatad (Loeb). 



X Asterias ochracead (Hagedoorn, 



Loeb) . 

 X Asterinad (Loeb). 

 X Chlorosiomad (Loeb). 

 X Mytihisd (Kupelwieser) . 

 X Pycnopodiad (Loeb). 



Toxoptieustes 9 



X Echinaster d (Tennent). 



X Hipponoe d (Tennent). 



X Holothuria fioridana d (Tennent). 



X Mellita d (Tennent). 



X Moira d (Tennent). 



