JONES. -j PALiEO'/OIC OSTRACODA. 69 



This seems to differ from all known forms. Tt has the Loperditian 

 shape of TsochiUna, although no buIcus nor tubercle is visible, and may 

 be named I. Amu, after Mr. H. M. Ami, iM.A., F. G. S., of the (ieolo- 

 gical Survey of Canada, who has done much in furthering our study of 

 the Paheozoic Ostracoda. 



From the Trenton Limestone of Lorette, Province of Quebec, col- 

 lected by Mr. 11. M. Ami in 1888. 



12. ISOCHILINA LABELLOSA (sp. nOV.). 



Pi. 10, ligs. K) a, b, c, 17, and 19. 



Leperditia, sp. nov. ? Quart. Journ. Geol. Sot'., vol. XLVI, 1890, p. 553. 



Length, (liin^o-liue,) Jieight, tliicl-cness. 



Fig. IG 1-2 (-86) -80 •() mm. 



Fig. 17 1-2 (-93) -73 mm. 



Fig. 19 2-7 1-4 mm. 



Small, darlv coloured, convex carapaces, having the dorsal line 



straight and long, the greatest ventral curve in the middle or nearly 



so, the front end subangular and the hinder end well rounded. The 



greatest height and greatest thickness are a little behind the middle. 



These have a ijeperditian form, with slight sulcus and tubercle in some, 



but none apparent in others. Though the individuals vary in relative 



proj)ortions, they have the same characteristics as to general shape and 



conditions of the valves. They are proportionally longer than 



Isochilina Whiteavesii, (tig. P> a,) and are narrower in front, with a 



shelving antero-ventral margin. Although so very Leporditian in 



shape, the valves meet ventrally without overlap, as in Isochilina] but 



the left valve is slightly thicker at its edgo than the other. This 



feature, however, does not correspond with the overlap in .Leperditia, 



as it is not on the overlapping valve of that genus. Having rather 



thick lips, this form may be termed I. lauellosa. 



Abundant, especially on the bed-planes, in a black limestone of the 

 Chazy Series, at Broad street, Aylmer, Quebec (figs. IG and 17). 

 C/oll. Mr. T. W. F. Sowter. Also free specimens from the Bird's-eye 

 and "Black-river Limestone (see fig. 19), associated with Tetradiuni 

 jibratum, Orthoccras miUticameratum, Bathi/Mnis extans, kv., at Lot 3, 

 Concession 3, River Front 1, Gloucester Township, Co. Carleton, On- 

 tario : where it was collected by Mr. W. Iv. Billings, of the Public 

 Woi'ks I)ej)artment, Ottawn. 



2 



