The maculæ are distinguished from all other sorts of maculæ, excepting those of Megalaspis, in being, as it were, shelved on a sort of support, formed through the bulging of the hypostomic surface just below them, one such console for each. Their surface lies consequently almost rectangularly to the adjoining surface of the hypostoma. They are white and smooth. =Niobe frontalis= ANG. Pl. V figs. 19-21. The pocketlike consoles are shorter and broader than in N. læviceps and the maculæ also larger and of an elliptic shape. In a horizontal section near the surface the macula has a speckled appearance of black dots, indicating an undeveloped prismatic structure, much more primitive than in the Asaphidæ. =Niobe læviceps= ANG. Pl. V figs. 22-26. It differs from the preceding through longer consoles below the maculæ, which are oval and in a horizontal section exhibit the same spongious structure, pl. V fig. 25. The cephalic eyes consist of polyedric prisms, which through deterioration show a central cylindrical core surrounded by darkish matter like Asaphus. The passage from solid, homogenous prisms to changed ones is most evident in the figure 22. =Ogygia= BRONGN. Figures of the maculæ are found in _O. Buchi_ SALTER, Mem. Geol. Surv., Dec. II pl. VI fig. 3 p. 2, where it is stated that »there are two transverse furrows near the apex, with compressed tubercles between them» There are two narrow crescentic maculæ and between them a little lower a longer, crescentic ridge, which may be the ridge that in other species connects the maculæ. Moreover, the shape of the hypostoma is not concordant with that of the other species. In Monogr. Brit Trilob. pl. 15 figs. 2, 3 there is only a reproduction of the former figure. _O. corndensis_ MURCH. SALTER in Monogr. pl. 16 fig. 10 interior side of the hypostoma with two lateral maculæ. In the description two pairs of furrows the uppermost is the maculæ. H. WYATT-EDGELL »On the Genera of Trilobites Asaphus and Ogygia and the Subgenus Ptychopyge» in Geol. Magaz. 1867, p. 14, 15 fig. 2 probably a cast with two oblique impressions of maculæ. _O. dilatata_ (Asaphus) SARS var. Sarsi ANG. SARS in Isis 1835 p. 342, pl. IX fig. 11. The figure has two small maculæ near the posterior margin and the author says »mit einer starken Vertiefung oder Einschnitt an jeder Seite des Endes». ANGELIN pl. XLII fig. 1 _b_. BRÖGGER'S fig. 38 pl. 3, in II, collies near to the specimen, which is described below, also belonging to Dr. G. HOLM. =O. dilatata= var. =Sarsi= ANG. Pl. V figs. 27, 28.