PROBUCTBS Martini, 
TAB, CCCXV II. — Figs. 2, 3, and 4. 
Spec. Char. Semicylindrical, convex above, 
with a flattened front, deeply striated, spi- 
nous ; lesser valve nearly flat, deeply in- 
serted ; hinge line equal to the width of the 
shell. 
Syn. Anomites pro ductus. Marlin Pet . Derb. 
tab. 22. f. 1, 2, and 3. 
This is the Pro ductus spoken of at p. 158 of the first 
Vol. of this work ; it is distinguished from every other 
by the width of its hinge, the neatness of its rather 
distant stria;, and the great length of its produced 
front : the ridges between the stride are often furcated 
upon the front, where also all vestiges of spines in 
general disappear : very seldom are spines found in 
connexion with any part, but the casts shew the roots 
of spines scattered over the convex surface, and dis- 
posed in two rows upon each ear : the few spines [ have 
met with are long and pointed. 
Not uncommon in the Derbyshire Limestone. Fig. 4 
represents a cast in ochracious sandstone, from the river 
Barn, in Yorkshire ; favoured by Mr. Danby some years 
ago. 
Fig. 3 is from a large, very concave, specimen, some- 
what corrugated, and thus intermediate between P. 
Martini and the following. 
PRODUCTUS antiquatus. 
TAB. CCCXVIL — Figs. 1, 5 and 6* 
Spec. Char. Semicylindrical, short, very con- 
vex above, longitudinally sulcated and trans- 
versely corrugated, spinous ; lesser valve 
nearly flat ; hinge-line shorter than the 
width of the shell. 
Syn. Annomites semistriatus ? Martin Pet. 
Derb. tab. 32 and 33. f, 1, 2, 3, and 4. 
Distinguished from the last by its less regular stria?, 
and in being corrugated ; the sides near the hinge are 
particularly rugged ; it is in general also a larger and 
shorter sheik 
