(IKAITOI.ITES OF XI'.W YORK, PART 2 



193 



thecae and two gonangia (the latter opening in the corners between the 

 thecae on the reverse side of the branchlets). The "budding- individuals," 

 the third group of individuals do not empty to the outside and are hence 

 not observable in an external view. 



In the series of sections which we copy here from Wiman [text fig. 94.] 

 the separation of a branch with its four individuals and a budding indi- 

 vidual at the lower end in figures F and G, are seen. 



A. musciformis differs from A. suecicus in having a Q-reater 

 number of individuals in each branchlet. 



Fig. 94 Series of thin sections of Acanthograptus suecicus (Wiman). The following table explains the lettering; 



Generation Gonangium Theca Budding individual 



1 .... b .... 



2 a b, .... 



3 e 1 



4 a, b„ 



5 c, 2 a 



Fig. 95 Acanthograptus suecicus (Wiman). Fragment of specimen 

 Fig. 96 Acanthograptus musciformis (Wiman). Branch, x 10 



No individuals open on the branches of Acanthograptus but all indi- 

 viduals originate in them, in groups of three (designated as nourishing 

 individual or theca, gonangium and budding individual), as the thin sections 

 here reproduced show. 



Acanthograptus is according to Wiman's observations a true genus of 

 the Dendroidea, with a structure corresponding to that of Dendrograptus 

 and Dictyonema. " The only difference between this species (A. sueci- 



