GRAPTOLITES OF NEW YORK, PART 2 441 



The last mentioned specimens suggest in their general habit, a coarse 

 Diplograptus euglyphus, but are broader (width i mm— 1.8 mm), 

 their thecae are arranged more closely (10-11 in 10 mm), their projecting 

 ventral margins separated by smaller intervals and their nemacaulus is broad 

 and straplike. The distal portion of the thecae is slightly inclined to the 

 axis of the rhabdosome, as shown in its ventral margin ami the apertnral 

 margin is horizontal or slightly inverted. The apertural excavations are 

 well rounded, but shallow, occupying about one fourth to one fifth of the 

 width of the rhabdosome. The sicular extremity of C. caelat us has in 

 common with Lapworth's drawings a stronger development of the virgella 

 and the lateral spines, shown in a fragment. 1 



Climacograptus cf. oligotheca Gurley 



Plate 28, figure 27 



Climacograpsus oligotheca Gurley. Am. Jour. Geol. 1896. 4:76 



Dr Gurley has described this species from the Upper Diccllograptus 

 zone at Magog, Canada and stated that it is closely allied to C . antiquus, 

 but usually longer and has but 12 to 14 thecae in 25 mm, while C. 

 a n t i q u u s has 20 in the same space. 



We have not observed this species in the Trenton shales of New York, 

 but find in the collections of the National Museum from Arkansas a speci- 

 men which has been labeled C . antiquus van oligotheca by Dr 

 Gurley, and which fairly well agrees with the description of the Magog 

 species. This is evidently also the C . antiquus ? listed in the same 

 publication | p. 297, 305] from Arkansas. The specimen like most of the 

 Arkansas graptolites of that suite is so badly flattened and thinned out that 

 its outlines have become somewhat obscured and no good camera enlarge- 

 ment could be obtained. We give here a figure of the specimen, interest in 



'From the careful description and excellent figures of C. antiquus since pub- 

 lished in tiie fifth instalment of the Monograph of British Graptolites, it becomes apparent 

 that our western specimens are narrower but in all other characters agree well with the 

 British types. 



