GRAPTOLITES OF NEW YORK, PART 2 383 



the same aspect as Grapt. spinulosus, i. e. exhibiting but the 

 straight spines of the lateral faces. 1 



A characteristic feature of this type of graptolite is seen in the earlier 

 growth stages. They are among the most striking objects of the Nor- 

 manskill shale [text fig. 331-35] and differ by their pear-shaped out- 

 line and multispinose sicular extremity from the early stages of all other 

 associates. The plump form is partly due to the wide sicula and still more 

 to the broad stout shape of the first thecae. Each of the latter is protected 

 by a long needlelike straight spine, projecting obliquely upward from the 

 middle of the outer margin [see fig. 22], but apparently taking its origin 

 from the apertural margin of the sicula. 



The specimens from the shales of Normanskill age in Alabama are 

 distinguished by greater length (40 + mm) and greater width (that of 

 lateral face = 2 mm) from the New York types, but do not seem to differ 

 in other respects and their thecae possess an equally close arrangement. 



Glossograptus ciliatus Emmons mut. horridus nov. 



Plate 26, figures 8, 9 



A comparison of the specimens from Summit, Nev., referred by Lap- 

 worth and Gurley to G . ciliatus, with the typical material from the 

 Normanskill shale of New York, brings out the existence of differences 

 which are important enough to call for a separation of this western form 

 as a mutation at least. The fact that the Nevada specimens occur in a 

 faunule that has no species in common with the Normanskill fauna and 

 represents an earlier zone, renders it already probable that the two forms 

 are different. 



In G. ciliatus mut. horridus, as we will call this mutation, 

 both the apertural and lateral spines are fully twice as long as in the typical 



1 In the light of the facts obtained from the finely preserved Normanskill shale speci- 

 mens of Glossograptus, it becomes also very doubtful. whether the two species, G. e c h i- 

 natus and G . h y s t r i x, described by the writer in Memoir 7 from the third Deepkill 

 zone, are specifically distinct, for their difference is mainly of the same nature as that 

 between G. ciliatus and G. setaceus. 



