The sections show that in _Ceraurus pleurexanthemus_ the anterior part of the alimentary canal was large, filling the part of the glabella below the heart; that the body cavity was provided with a chitinous dorsal sheath extending back into the thorax; and that the posterior portion of the mesenteron was likewise large and oval in section. Since the alimentary canal must be connected with the mouth and anus, some such restoration as that of Jaekel is indicated. No chitinous lining of the stomodæum or proctodæum was found, but it is not certain that any of the sections cut either of those regions. _Calymene senaria._ Ten transverse sections and one longitudinal slice show the form of the alimentary canal in _Calymene_. One of these has been figured by Walcott (1881, pl. 1, fig. 9) but without showing the organ in question. The only section cutting the cephalon which shows any trace of the canal is a longitudinal one (No. 141), which is not very satisfactory. It has a large, nearly circular, opaque spot under the anterior part of the glabella which may or may not represent a section across the anterior end of the mesenteron. Three sections (No. 9, 115, 143) show the dorsal sheath, the latter having the mud-filled canal beneath it. The sheath arches across the axial lobe as in Ceraurus, leaving room for the dorsal muscles at the sides and above it. In this region the canal is large and oval in section. Six slices cut the mesenteron behind the abdominal sheath (Nos. 39, 117, 148, 153, 62, 65) (see fig. 23). In the first four of these it is oval in section and large, but not so large as in No. 143. In the last two, it is small and circular in section, from which it is inferred that the canal tapers posteriorly. _Cryptolithus goldfussi_ (Barrande). Illustrated: Beyrich, Untersuch. über Trilobiten, Berlin, 1846, pl. 4, fig. 1c.--Barrande, Syst. Sil. Bohême, vol. 1 1852, pl. 30, figs. 38, 39. Both Beyrich and Barrande have shown that from the posterior end of the axial lobe to the neck-ring on the cephalon, the alimentary canal in _Cryptolithus_ has a nearly uniform diameter of less than half the width of the axial lobe. In front of the neck-ring, it enlarges, and while its original describers state that it extends only about halfway to the front of the glabella, Barrande's figure 39 shows it extending quite to the front, and his figure 38 shows it fully two thirds of the distance to the anterior end, as does Beyrich's figure of 1846.