144 ANNALS. NEW YORK ACADEMY OF SCIENCES 



J. Hall, who first described Callograptus, laid special emphasis on the 

 characters of the whole dendrome and as in this respect the new species, 

 C. grabaui fully agrees, it must be for the present referred to this genus, 

 even though the deviation in the aspect of the thecse shows two divergent 

 lines. of evolution among this "genus," similar to those in Dendrograptus, 

 Ptilograptus etc. The striation of the rhabdomes, which some authors 

 regard as an important feature of the genus, is not mentioned in the 

 early description of Callograptus salteri by J. Hall, while Euedemann 

 observed such longitudinal striations "when the thecal tubes have been 

 pressed through the periderm." This is also entirely the case in the new 

 species. 



There are three other genera of the Dendroidea which hold a median 

 position between Dictyonema and Dendrograptus and to which C. gra- 

 baui could be considered to belong. Odontocaulis is of quite the same 

 shape, but occurs a little later in Ordovician and Silurian time and 

 differs in its celluliferous stem. Calyptograptus, a Niagaran genus, 

 shows independence of the main rhabdomes clown to the root as an essen- 

 tial feature. Rhizograptus, in its genotype (the Magaran c 'bulbosus ,> ), 

 has branches, more or less reticulated, joined or overlain by others. The 

 dissepiments of C. grabaui are extremely rare, so that a position among 

 the true Dictyonema would be erroneous, likewise, a union with Dendro- 

 graptus seems to transgress the natural and originally assumed limits of 

 this genus, considering the presence of cross-bars and the shrub-like, or 

 perhaps even funnel-form growth of the polyparium. 



astogeny of dlctyonema plabelliforme in comparison with that 



op Staurograptus 



The collection of Columbia University contains such a number of the 

 earlier stages of the two genera that I was easily able to select a com- 

 plete series beginning with the sicula and closing with the full-grown 

 colony and this series is now preserved in the paleontological museum. 

 Still, only a few remarks can be added to the illuminating description of 

 Euedemann so far as the later stages of D. flabelliforme, as described by 

 this author, deviate in some respects from the normal ones presented by 

 "forma typica." All essential features, however, fully harmonize with 

 Euedemann' s observations. 



After the formation of the sicula, marked by a short, stout initial part, 

 on Dictyonema, by a slender, curved one on Staurograptus, the katem- 

 bryastic 18 series begins with the budding of the first, second and third 



18 E. R. Cumixgs : "Development of some Paleozoic Bryozoa," Am. Journ. Science, 

 Vol. XVII, p. 50. 1904. 



