M archantiacece. 
*59 
Santeria alpina, Peltolcpis grandis) growing, often intermingled, in 
several localities in the Bernese Oberland, and some additional 
details were made out in the structure and development of the 
sexual receptacles and of the sporogonia. 
In this group the ventral scales are arranged in several series, 
as in Corsinici. The scales do not show the sharply marked apical 
appendages which are characteristic of the Operculatse and 
Compositae; in this respect the Astroporae recall the Corsiniaceae 
and Ricciaceae. The air-chambers, which contain no assimilating 
filaments, are typically arranged in a single series, but in the median 
portion of the thallus they are divided up by secondary partitions. 
The capsule wall has well-developed fibrous thickenings in its cells; 
there is a small apical cap, and the capsule opens by irregular teeth. 
In Santeria and most species of Clevea the antheridial group is not 
sharply separated from the surrounding tissue, the antheridia being 
developed in long patches arranged in two irregular rows on the midrib; 
between the antheridial chambers, which have long ostioles, there 
are air-chambers, and the whole arrangement is hardly more definite 
than in various species of Riccia. In Clevea Ronsseliana we get the 
first step towards the differentiation of a definite male receptacle, 
the group being shorter and the antheridial chambers more closely 
approximated to each other. In Peltolepis the antheridia are 
developed in definite rounded cushion-like receptacles, sharply 
marked off from the thallus and surrounded by a series of scales. 
The chief interest of the group, however, lies in the organisation 
of the female receptacle (Fig. 18). In Clevea the receptacle arises 
as a dorsal outgrowth of the thallus tissue immediately behind the 
growing-point, which, after the young receptacle has been laid down, 
produces ordinary thallus tissue; and several receptacles may be 
formed in succession on the same branch of the thallus. The first 
archegonium is formed at the hinder end of the receptacle, and is 
followed by one at either side and finally one at the front. In the 
meantime the lower tissue of the receptacle has become a short 
stalk, which later lengthens out and carries up the receptacle with 
the sporogonia ; while the archegonia, which at first stand vertically 
at the edge of the receptacle, are carried downwards owing to 
growth of the tissue above them, and at the same time each 
archegonium becomes enveloped by a sheath which grows out from 
the surrounding tissue. The curved necks of the archegonia at 
first project freely from the sheath (involucre) and are directed 
upwards. Scales grow out from the tissue below the archegonia, 
