676 NEW YORK STATE MUSEUM 



l:e absent. Brogger cites it from the Pliyllograptiis shale of Krekliug in the 

 region of Christiana (according to Herrmann Lower Phyllograptus shale), and 

 Herrmann adds Scania and AVest Gothland. Tornquist's identification of 

 this species among the forms from the last named provinces is however not 

 recognized by the monographers of the English graptolite fauna, and its 

 occurrence in Sweden is hence still doubtful. 



Itemarhs. The reference list of the species shows distinctly by the num- 

 ber of erroneous identifications cited ho^v difiicult of exact recognition this 

 form is. The writer's experience verifies this fact; for, while in the lower 

 graptolite beds of the Deep kill a majority of the specimens readily suggest 

 hy their habit that they might belong to this species, a 

 comparison by measurements, Avith the types and the data 

 Fiff.72 Didymo- givcu by Hall, briugs out the fact that nearly all specimens 



graptus patu- .,-,.,., , , . 



ment^'^of*"' branch' '>scillate m their characters between the typical JJ . p a t ul u s 

 ^^^ ■ '^ and D . n i t i d u s . Hall states that the former species 



differs from the latter "m the greater extent of the stipes, and in their 

 almost lineal character " and adds : " The form of the denticles and their 

 angle with the axis, as well as their proportional distance, are distinctive 

 characters." Our material contains specimens of D. nitidus with stipes 

 that are longer and as straight as those of D . p a t u 1 u s. The graptolites, 

 here referred to D . p a t u 1 u s , have ^vider and more rapidly ^videning 

 branches, more inclined and curved thecae with mucronate apertural margins, 

 but the thecae exhibit constantly a somewhat closer arrangement than Hall 

 has recorded for D . p a t u 1 u s , and at the same time they are not so closely 

 arranged as in D . n i t i d u s. Our forms have also more rapidly expanding 

 branches which attain a greater width than either Hall's or the English types. 



Hall stated, further, that the inclination of the thecae in D . p a t u 1 u s 

 is 60° ; the thecae of our material have an initial inclination of 40°, which 

 hoAvever increases to 60° toward the aperture. The drawings of Hall's types 

 exhibit the same degree of curvature of the outer margin of the thecae. 



Lapworth, Elles and Wood also comment on the resemblance of D. 

 patulus and D nitidus, specially in the proximal region, and cite 



