CRITICAL BIBLIOGRAPHY. 15 
1839. In 1839 Murchison refers in his ‘ Silurian System,’ p. 88, to a letter 
from Prof. Phillips, describing three Unios and one modioliform shell from 
Ardwick, the latter of which he figures, p. 84, fig. c, and gives a woodcut of Unio 
acuta on p. 1085, fig. e, but he does not discuss further the nature of these shells. 
Prof. Phillips’s letter is as follows :—‘* This is a small shell from the Spirorbis 
Limestone of Ardwick, and looks so like a young Modiola that I hesitate to call it 
Unio. Tumid shell with prominent beaks, smooth, but with lines of growth, 
short straight hinge. In the argillaceous beds associated with the limestones are 
three Unios. The most common of these is nearly elliptical, hinge-line deviates 
considerably from parallelism, with front ends in prominent angle, lines of growth 
strong, shell thin, beaks slightly prominent. Professor Williamson refers this to 
Unio nuciformis of Hibbert inaccurately. It occurs in red beds, above limestone, 
black bass, and underlying coal-measures. 
“2nd Sp.—I have named Unio linguiformis (U. Phillipsii of Williamson), 
transversely elongated, three times as wide as long, hinge-line almost parallel to 
front lines of growth. Shell fine, thin, smooth. (Black bass.) 
3rd Sp.—Unio rugulosus, obliquely expanded, in semi-elliptical form, the 
hinge-line forming the diameter. Surface concentrically marked with broken 
undulations, showing radiations on posterior slope. Shell very thin, occurring in 
marls above limestones, black bass, and shale, beneath caleareous bands.” 
1833. Davreux, in his ‘ Essai sur la constitution géognostique de la Province 
de Liége,’ published in 1833, remarks at p. 101, ‘‘ Les Unios ou Myas, ou peut- 
étre Lingulz, se montre dans un grand nombre de nos Houillitres. . . . Ces 
bivalves fluviatiles se trouvent toutes en toit des couches, et n’ont jamais un 
volume trés considérable.” He figures— 
Unio acutus, Sow. 
- : 1. > fi > > : > > 
antiquus, Sow., be vee 8 23 
the latter a very characteristic cast of the hinge. 
1834. Prof. Phillips, in his article on ‘‘ Geology ”’ in the ‘ Encyclopedia Metro- 
politana,’ p. 590, speaking of the bands of marine shells in the Lower Coal- 
measures of Lancashire and Yorkshire, says, “In the midst of this series of 
Gannister Coal two layers of these shells occur ; one of them about the middle of 
the series, considerably above the ‘ Pecten Coal,’ and the other near the bottom, 
considerably below that coal.’ This paragraph is quoted by Mr. Binney in two 
papers on the marine shells of the Lower Coal-measures, ‘ Manchester Geol. Soc. 
Trans.,’ vol. i, p. 82; and vol. ii, p. 75. 
1834—1840. Goldfuss published his ‘ Petrefacta Germanica,’ p. 180, during the 
years 1834 to 1840, and he described and figured (tab. exxxi)— 
