1 8 NEW YORK STATE MUSEUM 



writer identified the material at the time with Dictyonema 

 f urcif erum, a species described by him 1 from the lowest 

 beds of the Deep Kill section. Later Prof. Thomas C. Brown 

 sent a slab with still better specimens from the same locality, but 

 labeled as Callograptus grabaui PI aim. 



As D . furcifer.um, occurring at the Deep kill in the upper 

 Tetragraptus and lower Didymograptus bifidus zone, is well suited 

 for a correlation of the bed holding this single graptolite in the 

 important and well-known Bellefonte section with the graptolite 

 horizons at the Deep kill, the writer has taken special pains to 

 compare the material and descriptions of D. furciferum and 

 Callograptus grabaui. The very careful description of 

 C . grabaui by the lamented Dr F. F. Plahn 2 leaves no doubt 

 that the C. grabaui is a synonym of D . furciferum, 

 the measurements agreeing completely. The number of thecae in. 

 10 mm shows a discrepancy in so far as 16 of them are recorded 

 for D. furciferum and 19 to 21 for the other species. The 

 first figure proves to be an average for mature branches in both 

 the Deep kill and Bellefonte specimens, the higher figure being 

 reached only in the proximal portion or the early nepiastic stage, 

 which, as is apparent from Doctor H aim's description, was alone 

 available to him. This fact and the further circumstance that the 

 lithographed original drawing of D . furciferum is poor, 

 are fully competent to explain the failure to identify the Pennsyl- 

 vania form with the Deep kill species. 



D. furciferum has received its name from the remarkable 

 bifurcate terminations of the apertural processes which grasp the 

 opposite branch (see Ruedemann, op. cit., text fig. 28, at lower end). 

 Doctor Hahn's material did not show this feature, as it is to be 

 observed only with difficulty unless the branches have been torn 

 apart. The specimens received from Bellefonte, however, show 

 this character much better than could be figured from the type of 

 D . furciferum. For this reason there are added here two 

 camera-drawings of detached branches w 7 hich show the various 



1 Graptolites of New York, pt 1, p. 606. 1904. 



2 Dr Felix F. Hahn. On the Dictyonema-Fauna of Navy Island, N. B. 

 Annals of the N. Y. Academy of Sciences : 22 : 142. 1912. Doctor Hahn 

 was killed early in the European War before Nancy. In him geology and 

 paleontology have suffered a grievous loss. The excellent paper here cited, 

 as well as several publications on Jurassic fossils and Alpine tectonics, prove 

 him to have been a keen and philosophic investigator who could not have 

 failed to achieve an eminent position in his chosen field. 



