_H. prima_ BARR. NOVÁK II Taf. I fig. 5. Two maculæ in continuation of a narrow groove, at the base of the central globosity. =Holmia= WALCOTT. _Holmia Lundgreni_ MOBERG, Sveriges äldsta trilobiter, Tafl. 14, fig. 10, 11, 12. The maculæ are much prominent and tubercular, elongate narrow, oblique but not mentioned in the description. Hypostoma probably belonging to the terrace-line group. As well seen in original specimens and in the figures in Dr. HOLM'S paper on Olenellus (Holmia) Kjerulfi there are also in this species two distinct macula; near the posterior margin of the hypostoma, above the marginal groove. =Homalonotus= KÖNIG. Maculæ have been previously observed in the following species. _Hom. delphinocephalus_ GREEN, HALL Pal. N. York vol. II pl. 68 fig. 11, incomplete figure with two well marked tubercular maculæ. No description. =Hom. Knighti= KÖNIG. SALTER II, pl. 12 fig. 10. Maculæ well expressed as oblique tubercles. On page 120 it is said »with a pair of lateral tubercles well developed (as in Asaphus ...)». This species is identical with ANGELIN'S Homalon. rhinotropis, Pal. Sc., pl. XX fig. 1 e and his figure has two hollow maculæ seen from the inside of the hypostoma. =Homalonotus Knighti= KÖNIG (= Homal. rhinotropis ANGELIN). Pl. IV figs. 20, 21. The maculæ lie as oblong, smooth tubercles surrounded by the irregularly grown granules of the surface, just below the central globosity of the hypostoma. In a preparation from the interior surface of the macula, as seen in transmitted light, fig. 21, this is white with only a few grey spots and on the superior border black streaks, lying obliquely. The substance of the shell around the macula is perforated by the minutest pores amongst which a few larger are intermingled. The granules are also perforated as those in Calymmene and the tubes continue through the shell, visible by their black colour. =Hysterolenus= MOBERG. _Hyst. Törnquisti_ MBG., En trilobit från Dictyograptusskiffern p. 320. In the descriptive letter-press, there is said, that in the exterior (lateral) parts of the anterior groove of the hypostoma a distinct tubercle is to be seen on each side. But none of the figures given, Pl. 17 figs. 6, 7, shows them or at least very indistinctly. =Illænus= DALMAN. It is remarkable, considering the great number of species in this almost exclusively Lower Silurian species, that there is none but a single species in which the maculæ hitherto have been delineated. This is Illænus angustifrons var. depresses HOLM I, pl. VIII fig. 18. A little, fragmentary hypostoma with globular maculæ. =Illænus Chiron= HOLM. Pl. IV figs. 22-25.