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 atropos J 1 (Tennent) . 



Arbacia pustulosa 9 



X Dorocidaris^ (Vernon). 



X Echinocardium d 1 (Stassano) . 



X Echinus & (Driesch, Stassano, 



Vernon) . 

 X Sph&rechinus J 1 (Driesch, Hert- 



wig, Stassano). 

 X Strongylocentrotus c? (Driesch, 



Hertwig, Vernon). 



Asteracanthion berylinus 9 



X Asteracanthion pallidustf (Agas- 

 siz). 



A sterias forbesii 9 



X Arbacia pustulatatf (Morgan). 



Dorocidaris 9 



X Strongylocentrotus tf (Vernon). 



Echinocardium cor datum, 9 



X Arbacia pustulosa 6* (Stassano, 



Vernon) . 



X Echinus^ (Vernon). 

 X Sph&rechinus c? (Stassano, Ver- 

 non). 

 X Strongylocentrotus $ (Vernon). 



Echinocardium rnediterraneum 9 

 X Echinus^ (Vernon). 

 X Sphaerechinus cJ 1 (Vernon). 

 X Strongylocentrotus c? (Vernon). 



Echinus acutus 9 



X Arbacia & (Vernon). 



X Sph&rechinustf (Vernon). 



Echinus microtuberculatus 9 



X Arbacia & (Driesch, Vernon). 



X Echinocardium c? (Stassano, Ver- 

 non) . 



X Echinus acutus tf (Vernon). 



X Strongylocentrotus cT (Driesch, 

 Hertwig, Vernon). 



X Sphcerechinustf (Driesch, Mor- 

 gan, Vernon). 



Hipponoe 9 ( = Tripneustes) . 

 X Cidaris c? (Tennent). 

 X Ophiocomatf (Tennent). 

 X Pentaceros J 1 (Tennent) . 

 X Toxopnenstestf (Tennent). 



Mellita 9 



X Moira tf (Tennent). 



Moira 9 



X Arbacia c? (Tennent). 



X Mellita tf (Tennent). 



X Toxopneitstes J 1 (Tennent). 



Psammechinus iniliaris 9 



X A sterias rubenstf (Giard). 



Psammechinus (pulchellus) 9 

 X Spatangustf (Kohler). 

 X Sphcerechinustf (Kohler). 

 X Strongylocentrotus tf (Kohler). 



Spatangus 9 



X Strongylocentrotus c? (Kohler). 

 X Psammechinus^ (Kohler). 



Sphcsrechinus 9 



X Echinus ^ (Driesch, Hertwig, 

 Morgan, Vernon). 



X Psammechinus tf (Stassano). 



X Strongylocentrotus 6 71 (Driesch, 

 Hertwig, Marion, Morgan, 

 Steinbruck, Vernon). 



X Antedontf (Godlewski). 



Strongylocentrotus lividus 9 



X Arbaciatf (Driesch, Vernon) . 

 X Dorocidaris tf (Kohler, Vernon). 

 X Echinus c? (Driesch, Vernon). 

 X Psammechinus c? (Kohler). 

 X Spatangus d 1 (Kohler). 

 X Splicer echinus $ (Hertwig, Koh- 

 ler, Morgan, Vernon). 



Strongylocentrotus purpuratus 9 



X Asterias capitatatf (Loeb). 



X Asterias ochraceatf (Hagedoorn, 



Loeb) . 



X Asterinatf (Loeb). 

 X Chlorostoma c? (Loeb). 

 X Mytilustf (Kupelwieser) . 

 X Pycnopodiatf (Loeb). 



Toxopneiistes 9 



X Echinaster & (Tennent). 



X Hipponoe c? (Tennent). 



X Holothuriafloridana o 71 (Tennent) . 



X Mellita tf (Tennent). 



X Moiratf (Tennent). 



