^{page 295 note 1} Angelin, Pal. Sueo.

^{page 295 note 2} Barrande, , Systeme Silurian, Vol I., Pl. 3, Fig. 7.Google Scholar

^{page 295 note 3} Salter and Woodward's Chart of Fossil Crustacea, Trilobita, Fig. 13.

^{page 295 note 4} Burmeister, Organisation of Trilobites, Tab. 3, Fig. 9.

^{page 296 note 1} Mr. Pengelly has more than once referred to this arch as a monument of sea action, and I noticed it in the Geol. Mag., No. 2, Vol. III. Feb. 1866, p. 68.Google Scholar

^{page 297 note 1} The late M. N. R. Bouchard, of Boulogne-sur-mer, wrote, a paper entitled “Observations sur les Hélices Saxicaves dn Boulonnais,” printed in Vol. xvi. of the “Annales de Sciences Natureiles,” in which he expresses his belief that these limestone perforations are the work of land-snails. M. Bouchard's observations were repeated and confirmed by Miss E. Hodgson, of Ulverstone (see Geologist, Vol. vii., Feb., 1864, p. 42).Google Scholar The late Dr. S. P. Woodward—than whom no higher authority upon Mollusca can be quoted—decided against the snail-theory, and referred the Ulverstone examples (presented by Miss. Hodgson, and preserved in the British Museum) to the decomposition of the rock by carbonic acid dissolved in rain-water— the form of the cavities often resulting from the former presence of fossils. The writer has seen numerous similar examples of weatheied and perforated limestone rocks at Gibraltar and elsewhere.—H.W.

^{page 297 note 2} The best preserved borings have retained the appearance of irregularly spiral ridges and furrows.