106 G. F. MATTHEW ON THE 



Okthoceras cf. Peiamus, Bill. (PI. VIL, figs. 13 a and b.) 



Palaeozoic Fossils, vol. i., p. 253, fig. 239. 



The form which may be provisionally referred to Billings's species is a straight shell, 

 expanding rapidly toward the large end, and ornamented with distinct, rounded annula- 

 tions about 2^ in the space of a centimetre ; these become irregular in width, and not so 

 distinctly raised at the large end of the shell as they are in its central part. The annula- 

 tions are themselves covered with lines or strife, of which about six are found on 

 each annulation. The striœ are thus not so fine as those of O. Priamus, and the annula- 

 tions are also wider apart ; furthermore Billings described the annulations in O. Priamus 

 as narrowly rounded, whereas in the form from the Suspension Bridge they are broadly 

 rounded. 



O. Lanmrcki, Bill., is also near this species, but is represented as having closer annula- 

 tions, and as tapering more gradually. 



Size. Only a part of the shell is known : this tapers from a width of two (2) 

 centimetres at the orifice to one (1) centimetre in a distance of 3| centimetres. 



Horizon and Locality. In the black shales of Div 2,d at the Suspension Bridge, St. 

 John. 



Possibly this shell is O. cornu-oryx, Whtfd., of the Chazy beds of Fort Cassin.' O. 

 attavus, Brog., of the Swedish Ceratopyge Limestone ^ is a more gradually tapering shell, 

 and the annulations are wider and not so directly transverse. 



Orthoceras cf Catulus, Bill. (PL VIL, fig. 14 a—d ) 



Palaeozoic Fossils, vol. i., p. 315. 



This species is a more gradually tapering shell than the last and the annulations are 

 further apart, they are irregular in their occurrence and inconspicuous in their relief, some 

 parts of the shell being smooth or nearly so. 



The siphuncle is cylindrical and is in contact with the side of the shell and is about 

 one-third of its diameter. The septa are strongly arched and there are two for each annu- 

 lation. There are about three or foiir septa in the space of the shell's diameter, and (on 

 the supposition that the specimens figured belong to one species) the septce are closer in 

 the larger end of the shell than the smaller. 



Sculpture. The surface is ornamented with numerous closely set engirdling striae, 

 somewhat irregularly spaced. 



Size. Only fragments of this species are known ; the largest is one centimetre across 

 and the smallest about half of that diameter. 



Horizon and Locality. Same as the preceding. 



This shell is allied to O. Catulus, O. Perseus and others from the Quebec group 

 described by Billings, which have the siphuncle in contact with the side of the shell. It 

 does not appear to agree exactly with any of them in the width of the annulations, or 

 distance and curve of the septa. 



1 Bulletin Am. Mus. Nat. Hist. vol. i., No. §, p. 320, PI. xxvii., figs. 1, 2. 



2 Die Silurischen Etagen 2 und 3, p. 53, Tab. x., fig. 16. 



