T. moni/ifer, Lam. T. nodulosus. Brand, is an elegant shell, and in 
the French specimens has its markings exceedingly well preserved. 
T. sulcatus, Lam. extremely like to T. granulatus, of Born. Tab. xn. 
Fig. 9 and 10, was obtained by Lamarck from the neighbourhood of 
Pontchartrain, as well as from Grignon. I found one specimen of 
this shell among the Harwich fossils, but which I have since broken. 
T. alligatus, Lam. is distinguishable by six transverse ribs, some of 
which are cord-like, and others crenulated. I have likewise found 
small specimens of this shell in the Essex cliff. 
Among the Veronese fossils is one which has a singularity of ap- 
pearance, proceeding from a slight convexity in the sides of the cone. 
It is formed of six whirls, on which are three rows of closely set, but 
distinct beads ; the base, which is circularly striated, possesses a con- 
siderable degree of concavity. From this circumstance it has been 
named T. concavus ; but as this property is very common, I should 
prefer the name T. convexus, from the convexity of its sides. 
Lamarck describes eight fossil species of this genus : T. crenularis, 
T. monilifer , T. sulcatus, T. alligatus, T. ornatus, T. subcarinatus, 
T. bicarinatus, T. agglutinans. 
Very large casts of this genus are found in different parts of Oxford- 
shire, Gloucestershire, and Somersetshire ; those in the neighbourhood 
of Bath being sometimes beautifully adorned with brilliant pyrites. 
XXXVII. Solarium. A depressed conical, nearly discoidal, um- 
bilicated univalve shell ; with the umbilicus crenulated or denticu- 
lated at the margins of the windings. The opening approaching to 
quadrangular. 
The shells placed by Lamarck in this genus, were included by 
Linnaeus in the genus Trochus ; and are sometimes difficultly distin- 
guished from the shells of this genus, as well as from those of the 
genus Planorbis. They are however, in general, plainly characterized 
by their large umbilicus, crenulated or denticulated at its sides. One 
species of this genus is found among the Hampshire fossils. Sola - 
