286 Aug. F. Foerste 
cardinal parts of the two valves had been more or less appressed 
posteriorly. 
Length about 50 mm., height 19 mm., height at beak 17 mm., 
extension of shell anterior to the beak 8 or 9 mm., convexity of a 
single valve about 5 mm. 
Type. From the Richelieu River at Chambly, collected in 1881 
by A. H. Foord. Both valves are present but only the right 
valve is figured. Associated with Glossograptus quadrimucrona- 
tus-approximatus) in the same rock fragment. Preserved in the 
Victoria Memorial Museum, by the Canadian Geological Survey 
at Ottawa, Canada. No. 8425. 
22. Orthodesma nasutum, Conrad 
(Plate III, Figs. 5 A, B; Plate T , Figs. 3, A, B, C) 
Orthodesma nasutum was described by Conrad from the vicinity 
of Rome, New York. It occurs, according to Hall, in the arena- 
ceous strata of the higher part of the group, and has not been seen 
in the underlying softer shales. The figure presented by Hall in 
the Paleontology of New York, vol. I, on plate 81, is from a defective 
specimen. The original of this figure is preserved in the State 
Museum at Albany, and is labelled as coming from Lorraine, in 
Jefferson county. The upper margin anterior to the beak is 
missing but sufficient is present to indicate that this upper margin 
was at a distinctly lower level than that part of the cardinal 
margin which is posterior to the beak. See Fig. 3, on plate V. 
According to my own observations Orthodesma nasutum is a 
fairly common species in the upper part of the Lorraine section 
of New York. It occurs at BennetFs bridge, about a mile down 
the river from the Salmon River Falls. Here it is associated with 
Rafinesquina mucronata, ordinary flat Rafinesquina alternata, 
Whiteavesia pholadiformis, Byssonychia radiata, Lyrodesma post- 
striatum, a species closely related to Ischyrodonta unionoides, and 
Archinacella pulaskiensis . The overlying layers, half a mile 
nearer the falls, contain also Pholidops subtruncatus but rounded 
anteriorly as in Pholidops cincinnatiensis, Catazyga erratica, 
Modiolopsis modiolaris, Clidophorus planulatus, and Cyrtolites 
ornatus. 
Specimens of Orthodesma nasutum occur also about a mile 
