Table 1.

Average dimensions and ratios of ventral and dorsal valves of Eohadrotreta zhenbaensis from the Cambrian (Series 2) Shuijingtuo Formation of the Three Gorges area, South China

Ventral valve	Lpr	Wpr	Lms	Wms	Lf	Wf	Lpr/Wpr	Lms/Wms	Lpr/Lms	Wpr/Wms
N	23	23	61	67	23	24	23	59	21	23
Mean	47	71	173	206	53	65	66.94%	84.76%	25.95%	32.27%
Min	40	58	125	146	25	52	53.25%	68.15%	20.48%	25.88%
Max	55	79	213	282	77	83	77.59%	97.52%	34.87%	42.53%
Median	48	70	173	203	52	65	66.23%	85.71%	25.81%	32.46%
SD	4	5	24	29	14	8	7.13%	6.80%	3.52%	3.61%
Dorsal valve	Lpr	Wpr	Lms	Wms	Lpr/Wpr			Lms/Wms	Lpr/Lms	Wpr/Wms
N	19	7	32	34	6			31	17	6
Mean	53	71	166	220	74.25%			74.96%	29.57%	33.77%
Min	40	60	114	186	60.00%			55.38%	21.14%	27.76%
Max	65	78	246	274	82.35%			93.90%	38.56%	41.94%
Median	53	74	159	214	74.55%			77.25%	28.82%	33.17%
SD	7	6	32	25	8.15%			10.89%	4.28%	5.24%

All measurements are in μm. Abbreviations: L_pr, W_pr length and width of protegulum, L_ms, W_ms length and width of metamorphic shell, L_f, W_f–length and width of pedicle foramen