GASTHROPODA. 73 
and Sutton. Possibly in the interval the shell may have undergone a slight change. 
Both forms of the shell, with the denticulations well shown, are not uncommon in the 
Middle Glacial of Billockby, but I have not seen it from either the Chillesford bed or the 
Lower Glacial sand. 
Rissoa senucta, 8. Wood. Supplement, Tab. V, fig. 15. 
Locality. Cor. Crag, Sutton. 
Length, sth of an inch. 
A single specimen of this genus, shown in the figure above referred to, has lately been 
found by myself, which I cannot refer to a known species, and I have therefore given to 
it provisionally the above name. ‘The volutions (about five) are nearly flat; the costa 
few (ten or eleven), large, coarse, and wrinkled; suture distinct, but not deep ; spiral 
strize large and distant; body whorl two thirds the length of the shell; aperture large 
and ovate. 
Rissoa reticutata? Mont. Crag Moll., vol. i, p. 108, Tab. XI, fig. 5. 
In the ‘ Crag Mollusca’ I referred this shell to R. reticulata, Mont., with a doubt. 
Dr. Hornes makes this Crag shell identical with R. Montagui, Payr., and in the list in 
Mr. Prestwich’s Coralline Crag-paper Mr. J effreys refers the Crag shell to “ 2. calathus, F. 
and H., not &. reticulata, Mont.,” while in his ‘ Brit. Conch.,’ vol. iv, p- 12, he says 
calathus is but a very doubtful species, and in his view only a variety of R. reticulata ; 
and then adds (p. 13) that S. Wood’s Crag shell called reticulata more resembles calathus 
than reticulata, and may be an intermediate variety. In this chaos of opinion I have 
thought it wisest to retain my shell under the designation given to it in the ‘Crag Mol- 
lusca,’ and with the same doubt. 
Rissoa Srrranist, Jeffreys. Crag Moll., vol. i, p. 106, Tab. XI, fig. 12 (as 2. 
costulata, 8. Wood). . 
Rissoa Srerantst, Jef. Brit. Conch., vol. iv, p. 36. 
This shell was described by me in the ‘ Crag Mollusca’ as a new species in ignorance 
that the name was preoccupied for other shells, as has been pointed out by Mr. Jeffreys 
in vol. iv, p. 36, of ‘ Brit. Conch.,’ who there proposed for it the name Sfefanisi. ‘This 
name I have therefore adopted. 
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