Table 2.

Embryological sources of mesoderm in spiralians^a,b.

	Species	Ectomesoderm	Endomesoderm	Reference
Nemertean	Cerebratulus	3a, 3b	4d	[26]
Polyclad tubellarian	Hoploplana	2b	4d	[9,24]
	Chaetopleura	None	3D	[8]
Mollusk	Patella	3a, 3b	3D	[25]
	Ilyanassa	2b, 2c, 3d, 3A, 3B, 3C	4d	[28]
	Crepidula	2c, 3a, 3b	4d	[10]
Annelid	Helobdella	1a (a'), 1b (b'), 1c (c'), 1d (d'), 3a (a'''), 3c (c'''), 3d (dm') 4d (DM'')	None	[27,32]
	Platynereis	1A, 1B, 1C, 1D	4d	[12]
	Capitella	2a?, 2c?, 3a, 3b?, 3c, 3d, 4d	none	This report

^aExamples included are taken from fate maps determined through use of intracellular lineage tracers injected into embryos at the 8-64 cell stage.

^bOnly blastomeres with confirmed mesoderm descendants are included.