106 THE GEOLOGIST. 
minutely perforated.* Exteriorly tlie surface is variously sculptured, and 
sparingly or closely covered with hollow tulnilar spines. It was also during 
the deposition of 1 he Carboniferous deposit s t hat 1 he greatest number of species 
and individuals prevailed, for as many as fifty species are said to occur ; out it 
is not always easy to distinguish certain forms whicli may after all be but 
varieties of some of tlic better determined or characterised species. It is very 
desu'able 1 o sec the complication of species disappear ; and when a single well 
defined species is made to absorb one or half a dozen old and unrecognizable 
ones, it is a favour to science ; and our constant efforts should tend to remove 
useless names from the uomenclatui'e, and seek the points of similarity with 
even more assiduity than the differences which we arc prone to exaggerate in 
the constant desLi'e to create new species. 
XXVI. — Pkoductus GiGAJJTEUs.f Martin sp. PI. v., figs. 1-4. 
Anomites giganteus. Martin, Petrif. Derb., pi. xv., fig. 1, 1809. 
This shell varies somewhat in shape according to age and specimen, but is 
nsually more or less transversely oval, and dilated at the sides. The hinge- 
line is straight, and generally exceeds in width the other portions of the shell. 
It usually possesses no hinge-area, but in some exceptional specmiens there ex- 
ists a rudimentary one, especially in the ventral valve ; no teeth or sockets ever 
existed for the regular articulatmg of the valves. The ventral valve is very 
LigTi. 8. — Proditcfns r]if)unten».% 
A, Interior of t,he Dorsal Valve. S, Interior of the Ventral VaJve, with the umbo removed. 
C, Ideal .section of both valves. Z), Hmge-line ot A ; j, cardinal process ; a, adducta, or oc- 
clusor ; r, divaricator muscles ; i, oral processes (?) ; s, hollows occupied by the spiral 
arms; v, vasculai- imiiressions ; A, hinge area. 
X These figm-es are by Mr. S. P. Woodwai-d ; more detailed representa,tions vrill be foimd 
in our plate. 
* For synonyms and more ample details on all that pertains to the species of Productus con- 
sult Prof, de Kouinck's excellent " Monogi-aphie des Gem'es Productus et Chonetes." Liege, 
1847. 
t Mentioned by Ure in his " History of Rutherglen and East Kilbride :" 1793. Page 316, in 
his Anomia; Behmatfe. 
