| Fig. | | Page |
| PLEUROSIGMA |
| 1 | Pleurosigma strigosum Wm. Sm. | [74] |
| 2 | Pleurosigma rigidum Wm. Sm. | [75] |
| 3 | Pleurosigma angulatum (Quekett) Cl. | [74] |
| 4 | Pleurosigma obscurum Wm. Sm. | [74] |
| 5 | Pleurosigma formosum Wm. Sm. | [73] |
| 6 | Pleurosigma naviculaceum Bréb. | [74] |
| 7 | Pleurosigma æstuarii Bréb. | [74] |
| 8 | Pleurosigma virginiacum H. L. Smith | [74] |
