JONES.] PALi^OZOIC OSTRACODA. 83 



valves) are not deep enough in the postero-ventral curve to match 

 Schmidt's figs. 5, 6, and 11, pi. 1, 1883, yet pi. xiii, figs. 1, 2, and 5 of 

 the left valve, match Schmidt's pi. 1, figs. 9 and 10; and our pi. xiii, 

 fig. 9, is near Schmidt's pi. 1, fig. 12, though rather contracted in front. 



L. Rlslngeri is smaller than L. balthica, obliquely-subovate, and not 

 suboblong like that species; it has a relatively shorter hinge-line, with 

 strong dorsal angles, and a more obliquely-curved postero-ventral re- 

 gion than L. ba'thica shows. 



PI. xiii, figs. 1 and 9 correspond with the typical L. Hisingeri in these 

 features. Several other individuals, for instance, pi. xiii, fig. 2, 3, and 

 5, approach closely to the foregoing in character, but have a rather 

 longer hinge-line (var. fabulina). In this respect, however, they are 

 like some of Schmidt's figures of the species, M(^m. Acad. Imp. St.- 

 Pdtersbourg, 1883, and may be retained as a variety under the specific 

 name. 



PI. xiii, fig. 4, is an elongate, oblique, narrow, left valve, with its 

 dorsal edge thickened for nearly all its length. We may call it vai'. 

 GiBBERA. Fig. 9 of Baron von Toll's L. Kotelnyensis, already referred 

 to (page 81), may be compared with our fig. 4; but the latter is 

 much smaller, more oblique on the ventral margin, and has a relatively 

 shorter hinge-line, and the dorsal thickening is longer and more 

 distinct. 



PI. xii, fig. 15 pi. xiii, fig. 2 are from a soft yellowish limestone, with 

 remains of Mollusca, at the foot of the Grand Eapids on the Saskat- 

 chewan River. 



A small right valve, length (r (hinge-line 4"5), height 4*, thickness 

 2*5, mm., not figured here, from Long Point, Lake Winnipegosis, is 

 much like pi. xii, fig. 15, in shape, but rather smaller, and is scarcely 

 distinguishable from Leperditia Louckiana, Jones (Ann. Mag. Nat. 

 Hist. ser. 3, vol. II, 1858, p. 245, pi. ix, fig. 16), except that the postero 

 ventral region is less obliquely projected and the hinder dorsal angle 

 less marked in the latter. The outlines of pi. xiii, figs. 2, 3, and 5 are 

 also much like that of JO. Louckiana, but they differ from it as to the 

 dorsal angles, and more or less in the antero-ventral slope ; they are 

 also too much rounded in front. From pi. x, fig. 5, it differs mainly 

 in having a bolder and deeper curvature of the ventral margin. 



Thus it is evident that Jj. JJouckiana is nearly a prototype of the 

 long-backed varieties of L. Hisingeri, just as Jj. anticostiensis and i. 

 amygdalina are two allied predecessors of the short-backed forms. 



Another specimen referable to L. Hisingeri, as one of its relatively 

 long-backed forms that have a sufficient downward obliquity in the 

 hinder moiety to separate them from L. balthica, is pi. x, fig. 5. It 



