60 



are five in number. Two of these are natural casts of the interior of the 

 brachial valve, both from New Hope, now ^ called Hespeler : the one 

 evidently that referred to as the "largest specimen seen," and the other, 

 (a gutta-percha impression of which is represented on Plate 15,) the 

 original of figure 152, printed inadvertently upside down, on page 168 of 

 the first volume of the " Palseozoic Fossils." One is a cast of the interior 

 of both valves of a small specimen from Gait. This is the original of 

 figures 4 and ia of Plate XIX. of Davidson & King's paper on the Tri- 

 merellidse, in the thirtieth volume of the Quarterly Journal of the Geo- 

 logical Society of London. The remaining two are casts of the interior of 

 the pedicle valve, with the inner surface of the beak and area also fairly 

 well preserved, both from Gait. The smaller of these two is the type of 

 Trimerella minor, Dall, and both are almost certainly the specimens upop 

 which Billings, Davidson and King based their descriptions of the beak 

 and area of the ventral or pedicle valve of the species now under consi- 

 deration. 



The genus Rhinoholus was based upon a gutta-percha impression of a 

 natural cast of the interior of a ventral or pedicle valve collected by Hall 

 at Gait in 1848. Billings, Davidson and King seem to have been fully 

 satisfied that the type of Rhinoholus is a ventral or pedicle valve of 0. 

 Galtensis, Billings, although Hall and Clarke appear to have entertained 

 some doubts on this point, possibly because they had not seen any 

 authentic examples of the pedicle valve of that species, which was not 

 figured by Billings. However that may be, it seems to the writer that 

 the characters of the two pedicle valves from Gait, upon which Billings 

 evidently based his description of that valve of 0. Galtensis, are essen- 

 tially similar to those of the type of Rhinoholus as described and figured 

 by Hall. 



R. Galtensis was collected at Gait by A. Murray in 1847 ; at Gait, 

 Guelph and New Hope (now Hespeler) by E. Billings in 1857 ; at Gait 

 and Guelph by Dr. R. Bell in 1861 ; at Hespeler by T. C. Weston in 

 1867 and 1871 ; and at Durham by J. Townsend in 1880-83. Most of 

 the specimens collected are natural casts of one or both valves, but a few 

 (six) brachial valves with the test preserved were obtained at Durham by 

 Mr. Townsend. On Plate IV. B (fig. 8) of the eighth volume of the 

 Palseontology of the State of New York, Hall figures " the interior of a 

 small brachial valve " of R. Galtensis, from Elora. The specimen from 

 Durham, figured on Plate 2, fig. la, of the first part of this volume, as 

 the pedicle valve of R. Galtensis, has the cardinal area completely covered 

 with the matrix and the interior filled with dolomite, so that its identi- 

 fication with that species is by no means certain. 



