On Trichites, a fossil genus of Bivalve Mollusks. 348 
mucous matrix, and are neither fasciculated nor laciniated at 
their ends ; they are so very slender that the triplet is not suffi- 
ciently powerful to afford a proper examination. I was unable 
to perceive either dissepiments or sporangia. In no respect, 
except in their parallel arrangement, did the filaments correspond 
with Morren’s description. 
PiaTe IX. fig. 8. a, portion of stratum from Lough Neagh ; 4, filament. 
XXX.—On Trichites, a fossil yenus of Bivalve Mollusks. 
By Joun Lycert, Esq.* 
[With a Plate. ] 
Tuts generic form is distributed over an extensive area both in 
this country and upon the continent ; it occurs in more than one 
of the oolitic formations; the Cotteswold Hills more especially 
produce it abundantly ; nevertheless it is almost entirely absent 
from the cabinets of English collectors ; and if we examine that 
section of modern literature which professes to illustrate fossil 
conchology, our search will scarcely be more successful or satis- 
factory. In both cases the defect may be accounted for by a dif- 
ficulty almost insurmountable experienced in obtaining illustra- 
tive specimens in a condition perfect, or even approaching to 
perfect ; fragments indeed are easily detached, but these alone do 
not convey any precise or adequate idea of the generic characters. 
The shells are large, the very Titans of their period, sometimes 
extending to upwards of a yard across, of a thickness far sur- 
’ passing that of bivalves generally, but of a structure peculiarly fra- 
gile (prismatic crystaliine), consisting of fibres closely arranged, 
placed perpendicularly to the surface and breaking readily m the 
direction of the fibres with any slight concussion ; this is a serious 
obstacle to their separation, to which may be added, that the up- 
per ragstone bed of the Inferior Oolite in which they most com- 
monly occur is very hard and intractable in the nature of its 
fracture. In almost every open quarry of this rock, and more 
especially in the stratum called Trigonia grit, these thick fibrous 
masses may be noticed; more rarely also in the middle portion 
of the same formation and in the shelly beds of the Great Oolite. 
They have usually been referred to a gigantic species of Pinna, 
probably from a similarity of structure. The Cotteswolds have 
produced two species, which are distinct from another recorded 
from the Jura which will subsequently be noticed. Dr. Plott, 
the historian of Oxfordshire, appears to have been the first per- 
son who applied the term Trichites to these shells. Woodward, 
* Read to the Cotswold Naturalists’ Club, Jan. 22, 1850. 
