178 



TWENTIETH REPORT ON THE STATE CABINET. 



branches are sometimes united at irregular intervals by slender lateral 



processes. Except for the dark corneous or chitinous texture, these, in 



their general aspect, might be regarded as slender Bryozoans. 



From these forms there is an almost insensible gradation to the Dictyo- 



NEMA, in which the branches are connected by lateral bars, at nearly 



regular intervals, and the whole is developed in a funnel-shaped or 



flabelliform frond,* with angular cellules on the inner margins of the 



branches (fig. 11). 



Fig. 11. 



DiCTYONEMA RETIFGRMIS. 



There are certain other forms of graptolitefe, which, though possessing 

 linear, straight or slightly curving stipes and angular cellules, like the typical 

 species, have yet a different aspect, and do not so naturally fall into the 

 series. Among these we find Graptolithus diver gens (fig. 12), where the 

 bilateral relation of the parts is still shown, but the celluliferous stipes or 

 branches are arranged on the two sides of a slender rachis, and diverge 

 on each side from what appears to be the centre or initial point. 



Among numerous specimens there are some slight variations of these 

 characters, but not any essential differences. 



* The typical species of the genus are clearly funnel-shaped, and all the others may be 

 BO likewise; but we know some of them only in fragments, of such form as to render it 

 impossible to determiiie whether the entire frond may have been flabelliform or infundibu- 

 liform. 



