676 NEW YOUK STATK MUSEUM 



be absent. Broggei- cites it from the Pliyllograptus shale of Krekling in the 

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

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

 this species among the fonus 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 doubtftil. 



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

 ber of erroneous identifications cited how difficult 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 

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

 comparison by measurements, with the types and the data 

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



fraptus iiatu- -n • i • i t ^ • i t^ 



ment"""/'^' branch oscillatc m their characters between the typical D . p a t ul u s 



^^ ' * and 1) . 11 i t i d u 8 . Hall states that the former species 



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



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



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



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



that are longer and as straight as those ofD. patulus. The graptolites, 



here referred to D. patulus, have wider and more rapidly widening 



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 . patulus, 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 ^vidth than either Hall's or the English types. 



Hall stated, further, that the inclination of the thecae in D. patulus 

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

 however 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 



