_c._ PSEUDOCEPHALODIA. Under this section have been classified those cephalodia that are almost independent of the lichen thallus though to some extent organically connected with it, as for instance that of _Lecidea panaeola_ which originate on the hypothallus of the lichen and maintain their position between the crustaceous granules. The cephalodia of _Lecanora gelida_, as described by Sernander[473], might also be included here. He watched their development in their native habitat, an exposed rock-surface which was richly covered with the lichen in all stages of growth. Two kinds of thallus, the one containing blue-green algae (_Chroococcus_), the other bright-green, were observed on the rock in close proximity. At the point of contact, growth ceased, but the thallus with bright-green algae, being the more vigorous, was able to spread round and underneath the other and so gradually to transform it to a superficial flat cephalodium. All such thalli encountered by the dominant lichen were successively surrounded in the same way. The cephalodium, growing more slowly, sent root-like hyphae into the tissue of the underlying lichen, and the two organisms thus became organically connected. Sernander considers that the two algae are antagonistic to each other, but that the hyphae can combine with either. The pseudocephalodia of _Usnea_ species are abortive apothecia; they are surrounded at the base by the gonidial zone and cortex of the thallus, and they contain no foreign gonidia. E. AUTOSYMBIOTIC CEPHALODIA Bitter[474] has thus designated small scales, like miniature thalli, that develop constantly on the upper cortex of _Peltigera lepidophora_, a small lichen not uncommon in Finland, and first recorded by Wainio as a variety of _Peltigera canina_. The alga contained in the scales is a blue-green _Nostoc_ similar to the gonidia of the thallus. Bitter[475] described the development as similar to that of the cephalodia of _Peltigera aphthosa_, but the outgrowths, being lobate in form, are less firmly attached and thus easily become separated and dispersed; as the gonidia are identical with those of the parent thallus they act as vegetative organs of reproduction. Bitter’s work has been criticized by Linkola[476] who claims to have discovered by means of very thin microtome sections that there is a genetic connection between the scales and the underlying thallus, not only with the hyphae, as in true cephalodia, but with the algae as well, so that these outgrowths should be regarded as isidia.