GRAPTOLITES OF NEW YORK, PART 2 457 



jaws or possibly of conodonts which according to Hinde are found in the 

 Chazy rocks with the same black, luster. Thin sections made through a 

 few specimens and comparison ot the same with sections of worm jaws and 

 conodonts have, however, shown the impossibility of referring the bodies to 

 either of the latter since they are not solid as these but consist of an 

 exterior periderm and art interior calcite filling [see fig. 440]. But these 

 sections have also demonstrated the absence of internal thecal walls — 

 except as low internal ridges of the outer wall — another feature that 

 distinguishes the form from the Monograpti. 



On the other hand, the form of the fragments is well comparable 

 with that of Monograpti, as e. g. M . v o m e r i n u s ; the small size of the 

 apertures, which however in some specimens are well discernible, is also 

 in line with that of certain Monograpti and if it is further considered that 

 the bodies can not be readily referred to any other class of fossil organisms, 

 it appears as the most satisfactory course to attempt to reconcile the 

 refractory characters of the form with the structure of the graptoli'tes. It 

 seems then that all these features can be considered as forming one group, 

 indicative of the paracmic nature of the species. Since also a Monograptus 

 is reported from the Lower Devonic of Bohemia, the genus appears to have 

 actually persisted into that era and its representatives there would naturally 

 be expected to exhibit characters not observed where the genus was culmi- 

 nating. The extremely small size of the branches, the relatively thick peri- 

 derm and its external carinations and ridges and the restriction of the size 

 of the apertures are all readily explained as resulting from the unfavorable 

 conditions under which this gerontic form was struggling. 



The reduction of the internal thecal wall to ridijes, and the obscuration 

 of the transverse growth lines (for fine transverse lines have been distinctly 

 seen by the writer in the depressions between the carinations) are 

 very likely secondary characters, the former resulting from the small 

 size of the whole branches and the latter from the formation of external 

 excrescences. 



Since only small fragments of M. beech eri are known and neither 



