pituitary caecum, [392];

parietal eye, [395], [396];

kidneys, gonads, and genital pores, [399], [400], [403];

distribution, [426];

P. fluviatilis, [426];

P. marinus, [426];

P. planeri, ova, [428];

P. wilderi, spawning, [427];

larva, Ammocoetes stage, [428]

Petromyzontes, [425] f.