110 SUPPLEMENT TO GREAT OOLITE MOLLUSCA. 
Harpax Watront, Zyc. Tab. XXXII, figs. 1, 1 a, 1 4. 
Testa (valva dextra) magna, crassa, ovata, convexa, sub-auriculata, late adherente, 
radiatim costatis, lamellis incrementi crebris, crassis nodiferis et imbricatis, facie interno, 
tabula cardinali magno dentibus et foveis longissimis insigni. Valva sinistra depressa, 
crassa, lamellis ut in valva altera, tabula cardinali dentibus prominentibus, longissimis, 
obliquis, sulcis conformibus. 
Shell of large dimensions, the right valve with a very large surface of attachment, sub- 
auriculated, thick, ovate, convex, the surface radiately costated, with thickened, crowded, 
imbricated and elevated lamella of growth; the triangular hinge plate is very large, 
oblique, transversely striated; the diverging outer grooves which receive the dental pro- 
cesses of the other valve are large, deeply impressed, and exhibit in their course three 
deeper portions or pits adapted to the successive positions occupied by the anterior pro- 
jecting or bossed extremities of the dental processes in the free valve ; the adductor scar is 
very large and posterior. 
The left or free valve is thick, but less convex than the other ; the hinge area occupies 
upwards of two fifths of the length of the valve; the ligamental groove is narrow and 
deeply marked, but the other furrows are superficial; the outer diverging dental pro- 
cesses are lengthened and conspicuous, terminating anteriorly in projecting bosses ; the 
adductor scar is prominent and sub-central. In the specimen figured with the valves in 
contact, the right valve has adhered to a smaller specimen of the same species, whose 
exposed inner surface exhibits the usual characters of the /e/¢ valve. 
Our species is allied to Harpar calvus and H. senescens, Desl., from the Middle Lias 
of Calvados, but has more prominent rugose lamellz, and a larger hinge area in both the 
valves. In the left valve the anterior termination of the dental processes in bosses with 
corresponding pits in the furrows of the other valve, has no counterpart in the figures or 
descriptions of M. Deslongchamps, but as they do not appear to be equally persistent in 
all specimens their importance can only be small. 
Geological Positions and Localities. The Forest Marble of Farleigh Wick, Somerset ; 
collected by W. Walton, Esq., whose labours have been rewarded by the acquisition of 
several good specimens. ‘The interiors of the valves of this species have also been observed 
in the Great Oolite of Minchinhampton; in these instances, however, their external 
surfaces could not be disengaged. 
GervinitaA Wattont, Lyc. Tab. XXXII, figs. 4, 4 a, 4. 
Testa fragili, ovato-oblonga, valva sinistra antice conveva, postice eaplanata in alam 
hrevem producta, umboni prominente, apice acuto, subterminali, ala antica brevi, margine 
