218 Havnes : The genus Sphaerocarpos 



back to common ancestors, but have originated at different points from several anacro- 

 gynous prototypes." 



" The systematic position of the Anthocerotes is more difficult to determine, and 

 their connection with any existing forms known must be remote. While the structure 

 of the thallus and sporogonium in Notothylas shows a not very remote resemblance to 

 the corresponding structures in Sphaerocarpus, it must be remembered that the peculiar 

 chloroplasts of the Anthocerotes, as well as the development of the sexual organs, are 

 peculiar to the group, and quite different from other Liverworts. To find chloroplasts 

 of similar character, one must go to the green Algae, where in many Confervaceae very 

 similar ones occur. It is quite conceivable that the peculiarities of the sexual organs 

 may be explained by supposing that those of such a form as Sphaerocarpus, for example, 

 should become coherent with the surrounding envelope at a very early stage, and re- 

 main so until maturity. In Aneura we have seen that the base of the archegonium is 

 confluent with the thallus, in which respect it offers an approach to the condition found 

 in the Anthocerotes ; but that this is anything more than an analogy is improbable. 

 The origin of the endogenous antheridium must at present remain conjectural, but that 

 it is secondary rather than primary is quite possible, as we know that occasionally the 

 antheridium may originate superficially. In regard to the sporogonium, until further 

 evidence is brought forward to show that Notothvlas may have the columella absent in 

 the early stages, it must be assumed that its structure in the Anthocerotes is radically 

 different from that of the other Liverworts. Of the lower Hepaticae Sphaerocarpus 

 perhaps offers again the nearest analogy to Notothylas, but it would not be safe at present 

 to assume any close connection between the two. Of course the very close relationships 

 of the three genera of the Anthocerotes among themselves are obvious." 



"On the whole, then, the evidence before us seems to indicate that the simplest 

 of the existing Hepaticae are the lower thallose Jungermanniales, and of these 

 Sphaerocarpus is probably the most primitive. The two lines of the Marchantiales and 

 Jungermanniales have diverged from this common ancestral type and developed along 

 different lines. The Anthocerotes cannot certainly be referred to this common stock, 

 and differ much more radically from either of the other two lines than these do from 

 each other, so that at present the group must be looked upon as at best but remotely 

 connected with the other Hepaticae, and both in regard to the thallus and sporophyte has 

 its nearest affinities among certain Pteridophytes. The possibility of separate origin of 

 the Anthocerotes from Coteochaete-\ike ancestors is conceivable, but it seems more 

 probable that they have a common origin, very remote, it is true, with the other Liver- 

 worts. They may probably best be relegated to a separate class, coordinate with the 

 Hepaticae and Musci.'' 



Those who follow the Vienna Rules of nomenclature will 

 scarcely be inclined to deny that the first effective post- 1753 pub- 

 lication of the genus Sphaerocarpos is found in Boehmer's edition of 

 Ludwig's Definitiones Generum Plantarum, dated 1760. Strict 

 adherents of the "American Code," how r ever, may discover that 

 Sphaerocarpos was not here used in connection with a specific name 

 and that it is not " associable by citation with a previously pub- 

 lislieci binomial species." But Ludwig's reference to Micheli, the 

 real founder of the genus, makes the application of the generic 

 name and the type of the genus indisputable. Adanson, who 

 appears to have been the next author to mention the genus, chang- 

 ing the spelling of the final syllable to us, meets the American re- 

 quirements of effective publication no more closely than does 

 Ludwig. The name, in the Michelian sense, appears not to have 

 been used in the binomial form until 1 792, though, meanwhile, 



