KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 19. N:0 4. 7 



rience of the value of the different characters afforded by this class. It has been ob- 

 jected that the trinomial nomenclature introduced by some of these authors, accor- 

 ding to which most of the forms are ranked as varieties under a few species, would 

 involve some inconvenience in dealing with a systematic arrangement of the forms, and 

 on this account it has been of late recommended to return to the method of D'()R- 

 BIGNY, v. REUSS and others, which claims a separate designation of specific value for the 

 slightest modification of characters even when accidental a method quite out 

 of classical custom and not consistent with ontogenetic biology, the aim of which is 

 to attain a delineation of the origin, descent and affinity of the forms, as true and na- 

 tural as possible. With this end in view the true notion of species, that is to say 

 certain eminent points or landmarks within the masses of modifications, should not be 

 given up. 



The amount of difference between forms that warrants their establishment as 

 species must always be liable to a more or less arbitrary determination; but it may 

 reasonably be asked of careful observers, who cannot but be interested in keeping the 

 system free from the encumbrance of overcrowding with insignificant distinctions, that 

 they should use some discrimination in valuing the characters for specific distinction. 



If a model plan of arrangement for this and other classes of organisms were to 

 be ventured on, it ought to take the shape of a somewhat regular network, where the 

 nodes would indicate the species, the nearly equal amount of diversity between 

 which and relation to one another would be marked by the converging and diver- 

 ging internodes, while the more conspicuous varieties were to be placed on short lines 

 radiating from the nodes. It would then be disturbing to ones sense of natural order, 

 if a form of minor and inconstant divergence should be placed on a node. 



Thus I am fully convinced of the propriety of the plan introduced into de- 

 scriptive biology by LINNJEUS and to a larger extent than ever re-established by those 

 before mentioned English philosophers, considering it a most valuable and suggestive 

 step forward. As for the varieties or modifications of minor deviation, the more 

 conspicuous only should be designated in the usual Linnrcan way, and those which pre- 

 sent merely an individual or accidental difference should not be allowed to become an 

 encumbrance to the system, but mentioned only en passant. 



In a system founded on true morphological characters it must be quite improper 

 to distinguish one stage of growth by one appellation and institute a new genus for 

 another stage of the same species. Such names should be discarded as generic and 

 used merely to indicate a certain plan of growth. As such illegitimate genera must be 

 regarded: Clavulina, Bigenerina, Dimorpliina, Sagrina etc., as has been fully demon- 

 strated by PARKER and JONES. 



As for the synonyms appended to most of the species in this paper, the list is so 

 far incomplete as merely those created and used by D'ORBIGNY and his successors 

 are referred to, while those of his predecessors, with a few exceptions, are passed over, 

 their nomenclature having been so thoroughly treated of by the unsurpassed in- 

 vestigations of PARKER and JONES, that, for the present at least, it lies beyond my 

 purpose and even power again to review that part of Rhizopodology. Although in ar- 



