248 REPORT ON THE STATE CABINET. 



in regard to the internal structure of this genus, which can only be 

 satisfactorily explained by the examination of better preserved specimens. 

 Nevertheless, in its general form, structure and mode of growth, it is 

 shown to be quite distinct from other graptolitic genera. The three 

 species referred to this genus present differences which can only be 

 reconciled by supposing that the two sides of the stipe are very unlike 

 each other in form and external characters, as in Retiolites. 



The species for which I have proposed the generic name Phyllograptus, 

 present close analogies with the typical form of Diplograptus in the char- 

 acter of test and form of cellules. These, in their aperture and form, are 

 nearly quadrangular ; and the cell-partitions are apparently continuous 

 between the two sides of the cellules, and reach nearly to the central 

 axis ; characters which we find in Diplograptus. These forms, in their 

 great lateral extension, depart widely from their analogues ; but they differ 

 more essentially in their cruciform mode of growth, presenting an 

 arrangement of parts, as if four simple stipes (lilie those of G. hryonoides 

 or G. higsbtji) were joined together by the coalescing of the solid axes. 

 In this latter respect, and in their greater development in width, they 

 differ most essentially from all the other genera of this family of fossils. 

 These forms are illustrated on Plate iv of this memoir. 



In the typical species of Dendrograptus, as illustrated under the 

 generic description, and in some other species, we have a wide departure 

 from the typical forms of Graptolithus, as developed in the character- 

 istic species of the genus. The strong stem or trunk, which is free from 

 cellules, and which has apparently been fixed at the base; the irregular 

 branching, which has no bilateral, and apparently no definite arrange- 

 ment, such as observed in all the forms of true Graptolithus, are strong 

 points of dissimilarity, and furnish characters for generic distinction. 

 The stem and branches are unequally striated longitudinally, but the 

 form of the celluliferous branches and of the cellules offers no important 

 difference (except in the smaller dimensions) from those of the stipes or 

 branches of the usual form of graptolites with a single series of cellules. 

 In one species referred to this genus (the D. gracilis) there is some 

 departure from the typical form of cellules, and the body of the stipe is 

 contracted at intervals, while the form of cellule and cell-aperture is not 

 unlike some of the sertularians. 



The Genus Callograptus offers forms which are intermediate between 

 true Dendrograptus and Dictxonema. In these species, the form of the 

 cellules has not been full}^ determined. They are marked in one species 



