LOWER SILURIC SHALES OF THE MOHAWK VALLEY 



8 = 



Fig. 26 



Fig. 24 



Fig. 25 



Fig. 27 



Fig. 28 



Fig. 24-28. Lasiograptus (Thysanograptus) eucharis ( Hall ) . 



Fig. 24. Pyrityzed specimen showing fibrous thickenings of the margins. 

 Fig. 25. Specimen showing traces of the extra marginal lacework (lacinia). 

 Fig. 26. Specimen showing pyritized marginal thickenings and ventral proc- 

 esses. Fig. 27. Specimen with fairly complete lacinia. Fig. 28. Specimen 

 with a different aspect of the lacinia. All x 5. 



Originals of F'igs. 24 and 26 from Schenectady beds of Dettbarn quarry 

 near Schenectady, N. Y. ; those of Figs. 25, 2^, 28 from Canajoharie shale 

 Chuctenunda creek near Amsterdam, N. Y. 



The genus Lasiograptus has been extended by EUes and Wood in 

 their splendid ^lonograph of the British Graptolites (title 58, page 

 318), and several subgenera distinguished. Our species would 

 correspond to their subgenus Thysanograptus in which the thecae 

 are of the typical Amplexograptus form, and the ventral processes 

 unite to form a complete ventral lacinia. In its general dimensions 

 L. eucharis resembles the British L . h a r k n e s s i Nichol- 

 son ; it is, however, distinguished by the closer arrangement of the 

 thecae. 



In the Monograph of the Graptolites of New York, volume 2, 

 L . eucharis is cited as occurring in the Utica shale and the 

 " Trenton-Utica transition beds " of Panton, Vt. In our work, 

 carried on since the publication of that volume, we have found that 

 species also in the Snake Hill and Canajoharie shales which are of 

 Trenton age and in the Frankfort shale, so that the range of L . 

 eucharis is found to extend both below and above the Utica 

 shale. 



Glyptocrinus sp. 



The presence of a species of Glyptocrinus in the Snake Hill sand- 

 stone is proven by a calyx and numerous stems with the character- 

 istic alternajtion of larger and smaller joints. The calyx was about 



