As has been previously indicated (see p. 439), the conclusion might be drawn from Moberg's description and figures of this species, interpreted by the knowledge of the true structure of the Didymograptus polypary, that the structure of the proximal part could in no essential particulars be separated from that just described in D. minutus, Mut. Consequently the genus Isograptus, which was proposed by Moberg for the species in question, is not authorized—at least, as founded on any of the characters cited by Moberg. The differences between Isograptus and Didymograptus, to which latter genus the species is referred by Nicholson, ought to be, according to Moberg, that in Didymograptus “both stipes arise at somewhat different levels on the sicula,” and that “each branch is itself bilaterally symmetrical”; whilst, on the contrary, in Isograptus the stipes should “arise bilaterally symmetrical from the sicula,” and each branch is not itself bilaterally symmetrical. As we have seen above, in reality in Didymograptus the left stipe is not bilaterally symmetrical, and the symmetry in the right stipe is entirely the same as that which is described by Moberg in Isograptus, namely, obliquely near the base, because the stipes do not arise from the side of the sicula, but from the “connecting” canal.

It may be fairly asserted that increased geological interest attaches to the deeper workings of the Kimberley Diamond Mines as they proceed. The remarkable development of underground mining, following upon the amalgamation of interests, which was the outcome of the collapse of the surface workings in 1886, or thereabout, has offered better opportunities for observation, not only of the diamond matrix-material but also of the varying characteristics of the neighbouring rock formations.

Bearing in mind the statements made in the previous note, respecting the stratigraphical relations of the Grenville Series, and referring to the excellent account by my friend Dr. Bonney of his observations at Côte St. Pierre, and to some difficulties stated by him which merit attention, we may sum up the evidence so far, under the following statements:—

The successional order of the strata of the Crag of the Eastern Counties, and the grouping and relationship of the several members of this formation, are here described more especially with regard to the Foraminifera obtained from them. These remarks on the distribution of the Microzoa in the Crag are based upon the examination of material collected by myself during the past eight years, with the exception of some from Tattingstone and Gedgrave (zone g) kindly supplied by Professor Prestwich. The whole of this material has been worked over by Mr. Richard Holland and myself; and Mr. Frederick Chapman has given us some aid with the Tattingstone Crag. Whilst assisting lately in the production of Part II of the Monograph of the Foraminifera of the Crag, it has been necessary to re-examine the collections previously made by the late Messrs. S. V. Wood and W. K. Parker, and the work done by them, with Dr. H. B. Brady and Professor T. Rupert Jones; and in view of the desirability of having the latest information in a tangible shape, I have been led to put together some notes on the Crag and the Distribution of its Foraminifera for this Monograph, Part II. An Abstract of my memoir is now offered to the British Association, meeting at Ipswich in the centre of the Crag district.