The subject of the identity of the great shell (or rather cast), which occurs in the Scarborough Limestone, with the Corallian P. striata, was partly discussed in the “Corallian Gasteropoda.” The considerable abundance of this form on certain horizons in the Oolites, both of the north and south of England, and its complete absence from other horizons, has attracted considerable attention. Thus it appears alike in the Humphresianus-zone of Scarborough and of Cheltenham, but not, as far as I know, in lower beds. The Yorkshire specimens are not good enough to warrant any conclusions as to the specific difference between this and the Corallian forms; therefore it seems safer to follow the authors of the Great Oolite Mollusca in referring the White Nab fossils to Sowerby's species. Moreover, I have less doubt as to the propriety of this course after reading the very interesting remarks of MM. Terquem and Jourdy with reference to Bourguetia striata.

I Have recently obtained from the Borough Lee Ironstone several specimens of a Selachian spine, apparently new, and showing several features of a very interesting character.

By the kindness of Dr. Henry Woodward, Keeper of the Geological Department of the British Museum, I have been furnished with a list of shells which have the locality “Mead End” attached to them in the Edwards Collection in that Museum.

It is a trite observation that truths which lie at our feet may be overlooked by the wise, and discovered by mere accident, or the chance step of some casual passer-by.

In the Geological Magazine for July, 1871, Plate VIII. pp. 289–294, I published an article on the above subject, giving my views of the appendages of Trilobites, and reproducing the figure of Asaphus platycephalus, Stokes, showing traces of eight pairs of locomotory appendages, discovered by Mr. Billings in the Trenton Limestone, city of Ottawa, and described and figured by him (in Quart. Journ. Geol. Soc. 1870, pp. 479–486, and plates xxxi. and xxxii.). I also appended a note to Mr. Billings's paper (op. cit. 1870, pp. 486–488) on a palpus of Asaphus from the same locality, which is as follows:—“Having been requested by Sir William Logan to examine the Trilobite sent over by Mr. Billings from Montreal, I was led to compare it with certain specimens in the British Museum collection, presented by Dr. J. J. Bigsby, F.R.S., some years since.

The discoveries and investigations of palæontologists touching the question of ambulatory and branchigerous appendages of the Trilobites have been entirely ignored by many of the ablest workers in the science. The important evidence which Mr. Billings produced was unsatisfactory to both Dana and Verrill. In 1881, after many years of untiring labour, Mr. C. D. Walcott (in the “Bulletin of the Museum of Comparative Zoology at Cambridge College”) furnished most conclusive proof of the existence of appendages to the cephalic, thoracic, and abdominal divisions of Calymene, Ceraurus, and Acidaspis. He says: “the discoveries have been received in about the same manner” as those of Billings and others—with incredulity, and as “having little value.”