456 



NEW YORK STATE MUSEUM 



By way of bringing this description in uniformity with the others in 

 this monograph, we add the following data which we take from the type 

 material now in Yale University Museum and kindly forwarded to us by 

 Professor Schuchert : The fragments indicate an extremely minute rhabdo- 

 some, their length is but little more than i mm, theirwidth, inclusive of den- 

 ticles, not quite .2 mm, and the thecae number 

 70 to 80 in 10 mm ; the form is hence of excep- 

 tionally small dimensions and would seem to 

 indicate by this feature its position as last 

 decadent epigone of the once might}' family 

 of Monograptidi. The thecae are three and 

 one half times as long as wide, overlap about 

 one third their length and are inclined not 

 more than io° to the axis of the rhabdosome. 

 The denticle is slightly recurved, and acutely 

 pointed, somewhat clawlike. The aperture is 

 small, apparently restricted to the inner corner. 

 The surface is longitudinally striated or even 

 wrinkled and costate, while the transverse 

 growth lines, so distinct on most graptolites, 

 Gi^: 4 ^435 I o>pfo/ 5 Vn:';r£!m ,: i could not be made out. It seems hence that 



original drawings showing form of denticles. 



Fig. 43 6, 437, 438 Redrawing* of some of tne periderm was not onlv relatively quite 



the types. Fig. 439, 440 lhin sections of 1 J 'I 



typical specimens. Fig. 435 enlarged .\6; 1 • 1 1 1 r ' 1 J • I 1 



theothersxs thick, but also furnished with external excres- 



cences not observed in the Siluric graptolites. The branch presents there- 

 fore an aspect which is liable to suggest another taxonomic position than 

 that among the graptolites. 



The facts which combined appear to dispute the graptolitie nature of 

 these bodies are : their extremely small size, as compared with that of 

 other Monograpti ; the indistinctness of the apertures; the strong longi- 

 tudinal carinations and striae ; the absence o! transverse growth lines; and 

 finally their Devonic horizon. The small size, form and luster ol the deep 

 black bodies are quite apt to suggest that they were fragments ol worm 



439 



