286 NEW YORK STATE MUSEUM 



tion is io° and they are about four times as long as wide. Their ventral free 

 walls are approximately straight ; the apertural parts slightly introverted. 

 It will be seen from these data, that the characters of this form are 

 essentially those of a N . gracilis but that the branches are more robust 

 owing to greater thickness of the periderm and greater width of the thecae. 

 As Gurley has pointed out. the habit of this form resembles that of N . 

 gracilis; this observation and the like arrangement and length of the 

 thecae suggest that crassicaulis is but a variety of N. gracilis. 

 Mo-e complete material, however, will have to be obtained to clear its 

 relationship. 



Nemagraptus gracilis var. distans nov. 



Plate i6, figures 7, 8 



A few specimens from a bed at Glenmont exhibit certain extremes of 

 the characters of N. gracilis which while apparently barely sufficient 

 for varietal distinction, yet indicate a clear tendency to differentiation in a 

 certain direction. A characteristic specimen of this group is that repro- 

 duced in plate 16, figure 7. Its branches are more slender and flaccid than 



in the typical specimens and in conformance with this 

 character, the thecae are more loosely arranged, there 

 being counted but seven in 10 mm on the secondary 

 201 branches and five in the same space on the main 



Ficc. 200, 201 Nemagraptus 



nov. cl Eniargement P s P (x°s) 1 "f a por- stipes. There is also developed a smaller number of 



tions of branches of the two types 



of the variety secondary branches in specimens that approach matur- 



ity, as in the above mentioned example which has but five on one side and 

 six on the other, although they have already attained a length of more than 

 40 mm. 



This type is mainly conspicuous by the longer intervals between the 

 bases of the secondary branches, and the smaller number of the latter. Its 

 extreme development is represented in plate 16, figure 8. In the original 

 of this figure the stolonal thecae are more than 2 mm long and the main 

 stipes and branches exceptionally thin (but .2 mm wide). 



