482 NEW YORK STATE MUSEUM 



process. The collotype plates thus obtained, miss, it is true, the artistic effect 

 that so distinguishes the former illustrations of graptolites and specially the 

 beautiful engravings in Hall's Graptolites of the Quebec Group, but they are 

 clearly faithful representations of the specimens in natural size. 



As our facilities did not permit us the application of Lapworth's method, 

 which would appear to furnish the most satisfactoiy results, we have drawn 

 the outlines of all forms, which are enlarged by means of a vertically placed 

 compound lens with attached camera lucida, the light being furnished by a 

 Bausch illuminating lens. This arrangement necessitated very little slanting 

 of the slabs, and the slight distortion produced by the inclined position of the 

 slabs has been reduced to a minimum by the placing of the longitudinal 

 axis of the fossil in a diagonal position. These outlines have been reduced 

 by photography to a scale of mostly twice natural size, this small enlargement 

 being retained to secure more distinct representation of certain details 

 than the natural size drawings could furnish. The text drawings are 

 slightly reduced camera dramngs. The illustrations in natural size have been 

 traced with a lithographer's needle directly from the fossils on gelatin plates, 

 glued over the graptolites. After retracing on the other side of the gelatin 

 plate, the outlines have been transferred to paper by means of lampblack, 

 rubbed into the tracings. While this method can not give exact results with 

 minute objects and hence is subject to various sources of error, it not only 

 gives satisfactory results with larger fossils, but also saves much time and 

 labor. 



4 Terminology 



The terminology which is currently applied to the graptolite structure 

 has been transferred to this extinct class from the hydrozoans under the 

 assumption that the graptolites form a branch of the Cnidarians. This usage 

 can be objected to on the ground that the taxonomic relations of the grap- 

 tolites are not yet established. It seems however that, inasmuch as a 

 terminology is necessary, and the graptolites indeed in their structure show 

 more analogies and similarities to the Hydrozoa than to any other class of 

 living animals, a leaning toward the hydrozoan terminology appears most 



