T he trilobites described in this paper were mainly collected during the progress of the excavations at Comley, which formed one of the subjects of the Report of the Geological Excavations Committee of the British Association, read at the Dublin Meeting, 1908. The majority of the specimens were derived from the preliminary excavation in the fields, some 200 yards south of the well-known Comley Quarry. This excavation cuts transversely through the same set of beds as those that are worked in the quarry, and, though of only a very shallow depth, it exhibits the most complete section as yet exposed of the local junction between the Olenellus and Paradoxides divisions of the Cambrian. Between the Olenellus Limestone, which in the quarry yields Olenellus (Holmia) callavei , Lapw., and the Conglomeratic Grit, which in the same quarry yields Paradoxides groomii , Lapw., there is intercalated some 4 feet of grey limestone. Provisionally, I divide this into the following bands, in descending order I hesitate to assign any definite numbers or letters to these beds, until more is known as to their faunal characteristics, which will throw light on their natural grouping. All these limestones above the Olenellus Limestone contain black nodules of, probably, phosphatic matter. The trilobites occur as aggregations of many parts or fragments of parts, indiscriminately mixed three or four species together, and usually preserve their original form aud convexity. In most cases the test has also been preserved, either wholly or in part; and where this has been the case I