The Marine Invertebrate Fauna of the Lias would, if one consulted Morris's Catalogue of British Fossils, published in 1854, be regarded as exceedingly poor, especially in certain classes, relative to the thickness of the rocks constituting that system. Thus, I count, eliminating synonyms, 130 species of Cephalopoda, 5 of Gasteropoda, 57 of Conchifera, 37 of Brachiopoda, 1 of Crustacea, 2 of Annelida, 21 of Echinodermata, and 2 of Zoantharia, and if to these we add the fish and other forms of life, we obtain a total of 426 species of plants and animals. But during the lapse of 16 years, this number has been nearly tripled, and to those classes, which were either unrepresented or characterized by a paucity of species, great accessions have been made. Notably, the number of Gasteropoda has risen from 5 to 269; the Conchifera from 57 to 297, the Brachiopoda have been augmented by the addition of 39 species, the Corals now number 67, and the Polyzoa and Sponges, previously unrepresented, now have a place in the list.