HAHN, DICTYONEMA-FAVNA OF NAVY ISLAND, N. B. m 



The type specimen of Clonograptus proximatus (1895, pi. 48, Figs. 

 la, Id) proves to be almost identical with Enedemann's figure 23 on 

 plate 2, besides a slightly greater elongation of the thecse. Of these, I 

 have found distinctly 8 in 8 mm. of length of the branches, the latter 

 not surpassing 25 in number. The fork-like mode of branching seems 

 highly characteristic. 



On the same slab, the type of Bryograptus lentus Matth. (1895, pi. 

 48, fig. 2) is found, appearing at first glance very distinct from that of 

 " Clonograptus proximatus /' but here, too, 9 to 10 thecse of a breadth up 

 to .75 mm- are seen, showing the same aspect as Euedemann's figs. 19 

 and 21. Moreover, this slab exhibits another crowd of branches which 

 in part are completely identical with "Clonograptus proximatus," while 

 a few branches turned to side view show the real aspect of "Bryograptus 

 lentus." Here again, 9 thecae are recognizable in 10 mm. of length of a 

 branch which is 1.6 mm. thick and of the same shape as Euedemann's fig. 

 15. This group of Staurograptus has still greater importance, since three 

 individuals of medium size have their siculae preserved and present the 

 characteristic side view of Euedemann's fig. 6. As a great many other 

 specimens of the collection which formerly were determined as "Bryo- 

 graptus patens," and indeed readily conform to Matthew's fig. 4, on 

 plate 48, really belong to nepiastic stages of Dictyonema, 16 a similar 

 reference of the type of Matthew seems quite possible, but I have not 

 seen the type specimen, and thus this explanation may still be ques- 

 tionable. 



A few additional notes can be added to the description by Matthew 

 and Euedemann. 



The preservation showing the thecse in full size and the sicula is rare 

 on examples surpassing a diameter of 5 mm. The thecse, scarcely more 

 or less than 9 in 10 mm. length of the branch, are sometimes irregularly 

 exposed, 6 smaller ones being visible in 4 mm. of the distal end and 4 a 

 little coarser ones in 4 mm. of the proximal part of the same branch. 

 Young stages, especially when crowded together, are almost inseparable 

 from those of Dictyonema flabelliforme var. ruedemanni, while the bryo- 

 graptoid neanastic stages of D. flabelliforme var. acadica and conferta 

 are easily mistaken for the "Bryograptus lentus" aspect of laterally com- 

 pressed Staurograptus. The great thinness of the periderm of Stauro- 

 graptus, which never shows such a tubulose structure or wrinkling as in 

 the case of Dictyonema (compare the above), is a very remarkable fact 

 and helpful in distinguishing these two genera. In the same respect, the 



16 Compare Westerg&rd (4), pi. 3, figs. 5 and 6. 



