GRAPTOLITES. | AS 
relations, their geological value, or indications of differences in mode of 
development, I do not appreciate at the present time the force and value 
of the proposed generic subdivisions for the two, four, and eight-stiped 
species, or the presence or absence of a central corneous disc as indicating 
generic distinctions; since it is impossible to obtaim any aid from such 
designations for the references of the numerous fragments which are the 
ordinary form and condition in which we find the graptolites, and in which 
they must generally be studied. 
The form, mode of growth, and arrangement of cellules im all these 
several proposed genera, are so identical in plan as to afford no means for 
generic separation ; and although the same is true of the properly-ramose 
forms, yet I conceive it might have been convenient to adopt a term 
(Dichograptus or Cladograptus) indicating the ramose character of the 
stipes, regarding as true branches only the subdivisions which take place 
after the commencement of the cellules. 
The genus Wereograptus* of Geinitz, proposed by that author to include 
such forms as Wereites, Myrianites, and Nemertites of Murchison, and 
Nemapodia of Emmons, etc., can scarcely be admitted mto the family of 
Graptolitidse, since all the American species referred to the first three 
named genera have no texture or structure like graptolites, and (as I 
have elsewhere shown) appear to be referable to the tracks or trails of 
some marine worms or other animals upon the sea-bottom ; while MVema- 
podia is simply the trail of an existing slug upon the slightly lichen-covered 
surfaces of the slates.+ 
The genus Glossograptus of Emmons is founded upon a species of 
Diplograptus with ciliate appendages on the cell-margins ; and no char- 
acters are given to show its generic distinction. The typical species 
of Nemagraptus (NV. elegans) is apparently a part of an individual of 
Graptolithus gracilis, or of some similar species; while the relations of 
the second species of the genus (JV. capzllaris), an elongate, flexuous, 
filiform body with afew branches at irregular intervals, can scarcely be 
determined from the figure given. 
The typical and only species of Staurograptus t of the same author is 
a very remarkable form of extremely minute proportions. Its mode of 
growth and subdivision of stipes, if accurately represented in the figure, 
are unlike anything known among this family of fossils, and it merits 
generic distinction. 
* Nereograpsus: Die Verstein. Grauwacken formation, etc., Graptolithen, p. 27. 
+ These markings can be easily removed from the surface of the laminee by washing with 
water; and they can be traced over the exposed surfaces of the edges of the successive 
lamine. 
t Glossograpsus, Staurograpsus, Nemagrapsus: Emmons, American Geology, part ii, 
pages 108 and 109, 
