272 ‘On the Paleozoic Bivalved Entomostraca. 
ences are perceptible in outline and contour. ‘This species, 
however, with other smooth and still more Leperditioid forms, 
has been lately referred by me to a separate group, with the 
generic name Aparchites (Ann. & Mag. Nat. Hist. May 1889, 
pp. 384, 385), and this appears to be the best group to which to 
refer the specimens (from Wisby) here noticed, although such 
non-suleate Primitian forms are rarely so very symmetrical 
as these. 
1. Aparchites decoratus, sp. nov. 
(Pl XeV. tres 2a Oye) 
Proportions * :—L. 18. H.15. Th. 94. 
Carapace lenticular, almost circular in side view, with the 
dorsal margin partly straight ; equally convex on the sides, 
as shown by the elliptical outline in fig. 126, but rather 
fuller towards the dorsal than towards the ventral border 
(fig. 12c). Surface of valves minutely punctate except along 
a narrow area all round. 
2. Aparchites simplex, sp. nov. 
(Pl. XV. figs. 13 a, 5, c.) 
Proportions :—L. 18. H.14. Th. 9}. 
This smooth, convex, lenticular carapace much resembles 
Ap. decoratus, but it is rather more ovate, one end (anterior) 
being somewhat elliptically curved and with less boldness 
than in fig. 12a; the hinge-line takes up a greater portion 
of the dorsal margin, giving a definite local straightness, and 
the surface has no ornament. In these features there is some 
approach to Aparchites obsoletus, J. & H. (Ann. & Mag. Nat. 
Hist. December 1865, pl. xiii. fig. 12). 
3. Aparchites Lindstremit, sp. nov. 
(Pl. XV. figs. 14 a, 6.) 
Proportions :—L. 13. H.10. Th. 43. 
This is rather more Leperditioid than either of the two 
described above, and, excepting that the ends of its dorsal 
margin are not sharp and that it is less convex and very much 
smaller, it much resembles A. Whiteavesti, Jones (Ann. & 
Mag. Nat. Hist. May 1889, pp. 384, 385, pl. xvii. fig. 10). 
* For figures 12, 13, 14, the proportions are taken on the same scale as 
for figs. 1-11. 
