BRITISH 
SILURIAN BRACHIOPODE 
Famity—LINGULID. 
Or this family the genera Lingula, Lingulella, Obolus, and Obolella are represented 
in the British Silurian rocks." 
Genus—Lincuia, Bruguiere, 1789. 
In pages 199—205 of my ‘ Monograph of the British Carboniferous Brachiopoda’ I 
have given at some length the characters, both external and internal, of this genus; and 
thereto the student is referred in order to avoid repetition. 
It is, however, no easy matter, if even possible, always satisfactorily to distinguish the 
numerous so-termed species that have been referred to this genus, their shapes in many 
cases differing but little one from the other, not only in the Silurian rocks, but also 
throughout the entire sequence of geological formations. Many of these species are more 
or less longitudinally oval, with valves slightly convex, sides either straight or moderately 
curved, front straight or rounded, beaks more or less sharply acuminated. In such 
cases, where the general form appears to differ so little, it 1s almost impossible in the 
present state of our knowledge to point out, and especially by words, those very minute 
differences, real or imaginary, which may have been adduced as reasons for applying to 
certain forms aseparate specific designation. There are, however, in the number many 
well-marked and apparently distinct species, at all times easily recognisable. The recent 
species are few in number; but, besides a certain difference in their respective forms, 
most of them may be distinguished by their colour. Thus, Mr. L. Reeve describes Z. ovalis 
as of a brilliant verdigris-blue-green colour; LZ. ¢wmida is brownish- or reddish-olive ; 
LL. murfina of a peculiar coppery red tone of colour; ZL. adina and L. semen are whitish ; 
1 As, on account of its great length and the number of plates required, this Monograph must be 
issued in several consecutive portions, the author earnestly requests those who may possess species not 
described under the several genera will kindly communicate with him upon the subject. Additional 
information as to any of the species will find a place in the ‘‘ Supplement.” 
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