In the Geol. Mag. Dec. II. Vol. X. pp. 462–3, a Synopsis of the Genera of Fossil Phyllopoda was offered as a basis for the study of these interesting, though often obscure, little fossils, and some of the Bivalved forms, namely, Hymenocaris, Caryocaris, and Lingulocaris, were more especially noticed. See also “Report British Assoc.” for 1882. The univalve forms (excepting Dithyrocaris) have since then been carefully studied; and the classification proposed last year is found to hold good, with some slight modification, on comparison of all the species of which specimens or published figures have come to hand. Thus the term “flat-shield” is not strictly correct, for some of these carapaces are subconical or slightly convex; and one at least (Dipterocaris) is bent like a low ridge along the back: Pinnocaris is possibly really bivalved, without the triangular rostral piece; and probably Barrande's Crescentilla may be placed with Pterocaris and Dipterocaris.