1 1 2 Salmon.- — A Monograph of 
is characteristic of the genus. A ‘ central-strand * is not 
differentiated in the tissues of the stem. 
Although Streptopogon shows so close an affinity with 
Tor tula ( Syntrichia ) in the structure of the peristome that 
there can be no doubt that the two genera belong to the 
same family, it is certainly distinct generically in the lax 
areolation of the leaves, in the cells of which the primor- 
dial utricle is conspicuous, and in the mitraeform calyptra. 
Muller observes (18) with reference to the species of Strepto- 
pogon : ‘ Die Aehnlichkeit aller dieser Arten mit Syntrichia 
ist zwar eine sehr grosse der Tracht nach, . . . doch ist 
das Blattnetz beider Typen so abweichend, dass man einen 
Streptopogon selbst steril zu unterscheiden im Stande ist. 
Auch will mir scheinen, als ob es bei Streptopogon am 
Grunde des Blattes keine Zellen gabe, die wie bei Syn- 
trichia poros-durchbrochene Wande besitzen.’ It may be 
pointed out that the difference here alleged does not exist, 
since we find that in the lower cells of .S. erythrodontus 
the walls become in age strongly porose (see Fig. 7 ) ; the 
same appearance, though less marked, is also found in the 
leaf-cells of 5. rigidus , S. Lindigii , and 5. cavifolius. 
It must be noted also that two of the generic characters 
given by Wilson (see above), viz. ‘ calyptra mitriformis, superne 
scabra ’ and ‘ cellulae operculi contortae,’ require emendation, 
since in one species, 5. cavifolius , the calyptra proves to be 
glabrous, and in three species, 5. Lindigii , .S'. cavifolius and 
5. clavipes , the cells of the operculum are not spirally con- 
torted but arranged in straight rows. 
Before giving a systematic account of the species of the 
present genus, I wish to express my obligations to the 
authorities at the Berlin Museum for sending me on loan the 
types, or portions of the types, of several mosses in Muller’s 
herbarium ; to Mr. William Mitten, A.L.S., for very kindly 
and also ‘ companion- cells ’ for the German word ‘Begleiter* (cf. Lorentz, Stud, 
zur vergleich. Anat. der Laubmoose (Flora, xxv, 247, 257: 1867); also Mem, 
Grundl. zu einer vergleich. Anat. der Laubmoose (Pringsheim’s Jahrb. fur wissen- 
schaftl. Bot. vi, 374, 378 : 1867-8)). 
