258 THE VOYAGE OF H.M.S. CHALLENGER. 



Psilotum triquetrum, Linn. 



Psilotum triquetrum, Linn. ; Baker in Journ. Linn. Soc. Lond., xv. p. 112 ; Benth., Fl. Austr., vii. p. 

 681 ; Seem., Fl. Vit., p. 331. 



Admiralty Islands. — Spread over nearly all tropical and subtropical regions, including 

 the most remote islands of Polynesia. 



Psilotum complanatum, Swartz. 



Psilotum complanatum, Swartz; Baker in Journ. Linn. Soc. Lond., xv. p. 112; Benth., Fl. Austr., 



vii. p. 685. 

 Psilotum flaccidum, Wall.; Seem., Fl. Vit., p. 330, 



Admiralty Islands. — This species is as generally diffused in Polynesia as Psilotum 

 triquetrum, and nearly as widely in other parts of the world, except that it does not 

 appear to reach Africa, though common in the Mascarene Islands. 



CRYPTOGAMS.— CELLULA ES. 



MUSCI. 1 



Octoblepharum (Arthrocormus) schimperi, Mitt. 



Arthrocormus schimperi, Dozy et Molk., Muse. Frond. Arch. Ind., p. 76, t. 27, et Bryol. Jav., p. 25. 



Admiralty Islands. — Fine specimens, though barren. Amboina to Borneo and the 

 Philippines. 



Octoblepharum (Arthrocormus) incrassatum, Mitt. 



Octoblepharum {Arthrocormus) incrassatum, Mitt, in Seem. Fl. Vit., p. 386, t. 98, fig. g. 



Admiralty Islands. — Barren ; its fruit is as yet unknown. Described from Samoan 

 specimens. 



All the species of this group, and about ten are certainly known to belong to 

 it, have the leaves more or less distinctly tristichous in their insertion, and are composed 

 almost entirely of an iucrassated trigonous nerve, thus differing from the structure of the 

 leaf in the typical Octoblepharum albidum, where the iucrassated nerve is flattened ; and 

 there is no trace in the upper portion of the pagina of the leaf of a marginal limb, which 

 is more or less evident among the species allied to Octoblepharum schimperi, as well as to 

 those agreeing with Octoblepharum densifolium and Octoblepharum sqaarrosum (Leuco- 

 phanes), Brid. Bryol. Univ., i. p. 7G4 = Syrrhopodon candidus, Schwiigr., t. 183 = LeuGO- 

 phanes reinwcvrdtianum, C. Mull., Synopsis Muse. Frond., i. p. 82, Dozy et Molk., Bryol. 

 Jav., t. 1G, which have the dilated nerve so thin that its small medial carina is easily 



1 By William Mitten, A.L.S. 



