325 



" 0. Thestor, Hall,* is described as having proportionately finer an- 

 nulations, and 0. Idmon, Hall, (t) judging from the figure, is almost 

 cylindrical." 



Orthoceras Hagersvillense, Whiteaves. 



Plate 33, figs. 4 and 4 a. 

 Orthoceras Hagersvillense, Whiteaves 1898. Ottawa Naturalist, vol. XII, p. 126. 



" Shell of medium size, straight, longicone and increasing slowly in 

 thickness. Surface markings consisting of a fine rectangular reticulation 

 caused by the crossing of numerous equidistant and continuous, minute 

 and close-set, longitudinal ridges, by transverse but otherwise similar 

 ridges. In the only specimen that the writer has seen, the longitudinal 

 ridges are rather less than a millimetre apart at the smaller end, and 

 about a millimetre apart at the larger ; while the transverse ridges are 

 slightly closer together, especially towards the larger end. Septa, and 

 shape and position of the siphuncle unknown. 



" Corniferous limestone at Hagersville,'' Ont., collected by the writer 

 in 1890 : a slightly distorted specimen, about three inches long, and an 

 inch broad at the larger end, with a considerable portion of its surface 

 buried in the matrix. 



"The species seems to be well characterized by the minute reticulation 

 of its surface, though its internal characters are unknown." 



♦ Palaeontology of the State of New York, vol. V, pt. 2, p. 302, pi. 82, fig. 18. 

 + Idem, p. 302, pi. 43, figs. 11 and 13. 



