16 
I^AUTILOIDEA. 
1886. Orthoceras transversum, J. F. James, Journ. Cincinnati Soc. 
Nat. Hist. Yol. Tiii. No. 4, p. 239. 
Sp. Char. Section elliptical, tapering at the rate of about 1 in 6. 
Septa numerous and rather strongly arched. Siphuncle eccentric. 
Surface of the shell ornamented with fine transverse striae. 
Horizon. Cincinnati Group ( = Lower and Middle Bala ?). 
Locality. Cincinnati ; Ohio. 
Fairly well represented. 
Orthoceras laqueatum ?, HaU. 
1847. Orthoceras laqueatum^ Hall, Pal. of New York, vol. i. p. 206, 
pi. iii. f. 12, pi. Ivi. flf. 2, a, h, c. 
1852. Orthoceras laqueatum^ Owen, Geol. Surv. of Wisconsin, Iowa, 
and Minnesota, p. 626. 
1863. Orthoceras laqueatum, Billings, Geol. of Canada, Appendix, 
p. 950, referring only to pi. iii. f. 12, Pal. of New York {loc. cit.'). 
B]p. Char. Section circular or suhelliptical ; rate of increase 
slow, about 1 in 12. ‘‘ Surface marked by sharp, elevated, longi- 
tudinal ridges, alternating with finer intermediate ones ” (Hall). 
Siphuncle subcentral. 
Ileraarhs. The imperfect condition of preservation of the speci- 
mens renders their identification with Hall’s species rather 
doubtful. They show, however, traces of what would appear to have 
been longitudinal ridges, such as are figured by HaU (loc. cit. pi. Ivi. 
f. 2 a). 
Horizon. Trenton Formation ( = Bala Limestone Group). 
Locality. Montmorenci Falls, near Quebec, Canada. 
Fairly well represented. 
Orthoceras velatum, Blake. 
1865. Oi'thoceras velatum, Salter, MS., Cat. Foss. Mus. Practical 
Geology. 
1882. Orthoceras velatmn, Blake, British Foss. Ceph. pt. i. p. 87, 
pi. iii. ff*. 12, 12 a. 
Sp. Char. Section, though generally compressed, nearly circular 
in two or three instances, or at least equiaxial. Bate of increase 
in smaller examples about 1 in 9, but decreases at the larger dia- 
meters. The larger ornaments are gently undulating ribs, somewhat 
oblique, and distant 1- the diameter ; these are covered hy fine 
longitudinal and transverse riblets, each 18 per line, dividing the 
