BRACHIOPODA. 
93 
which has a wide distribution througii the lower and upper Carboniferous of 
England, Ireland and Belgium. 
SuBOENUS SE MINE LA, McCoy. 1844. 
This is another term proposed in the “ Synopsis of the Carboniferous Fossils 
of Ireland,” which has been absorbed into the genus Athyris by later writers. 
On page 160 of his work, McCoy mentions Seminula as “ a genus formed for 
the reception of those little species which have a minute perforation but want 
the deltidium,” and further, on page 158, describes the genus as follows; 
“ General Characteristics. —Shell small, subpentagonal; smooth or slightly 
plaited at the margin; beak of the dorsal valve small, with a minute perfora¬ 
tion; no deltidium. 
“ The species of this genus are all small; the margin frequently indented, 
but no distinct plaits on the surface; the outline is usually more or less pent¬ 
agonal ; the beak has a very minute foramen for the passage of the muscle of 
attachment, but there is no deltidium separating the foramen from the hinge. 
“ The genus is peculiar to the Palaeozoic rocks.” 
In this place the author described three species, the first of which, Seminula 
pentahedra, Phillips (sp.), may be taken as the type in absence of any specified 
typical species. Phillips’ species has been shown to be synonymous with Spir- 
ifer amhiguus, Sowerby, and is antedated by it. The other forms referred, in 
the work cited and subsequently, to Seminula by McCoy, have been shown by 
Davidson to be not congeneric with S. {Athyris) ambigua. No generic import¬ 
ance can now be given to the apparent absence of the deltidium in this shell; 
it is simply concealed as in many other Athyres by the incurvature of the 
beak. Mr. Davidson has described and elaborately figured the Athyris am¬ 
bigua* and from his work, with the aid of a series of specimens from the Car¬ 
boniferous limestone of Great Britain,! it appears that the shell has certain 
characters which do not permit its easy association with the other subdivisions 
of Athyris. The smooth exterior of the species, its subpentahedral form and 
* Carboniferous Brachiopoda, p. 77, pi. xv, ligs. 1(5-22 ; pi. xvii, tigs. 11-14. 1858. 
t For some of which we have been indebted to Prof. John Young, of the Hunterian Museum, Glasgow. 
