162 HIPPOPODIUM. 



HIBOLITHES. Montf. A genus composed of species of Belem- 

 nites, Auct. which are swelled towards the apex, and contracted 

 near the centre. B. Hastatus, Auct. fig. 468. 



HIMANTOPODA. Schum. Malleus, Auct. 



HINGE. The edge of the bivalve shells near the umbones, in- 

 cluding the teeth and ligament. 



HINNITES. Defr. A generic name proposed for PectenPusio, 

 Auct. remarkable for the irregularity of the outer surface, which 

 would almost lead to the belief of its being an attached shell. 

 Fig. 173, H. Pusio. 



HIPPAGUS. Lea. {Horse boat.) A minute fossil shell, re- 

 sembling Isocardia in form, but destitute of hinge teeth. H. Iso- 

 cardioides, fig. 128. 



HIPPOCHRENES. Montf. Species of Rostellaria, Auct. with 

 the outer lip spread. Fig. 403. R. Columbaria. 



H1PPONYX. ('l7r7roc, hippos, horse ; owl, onyx, nail or hoof.) 

 Fain. Rudistes, Lam. — JDescr. Inequivalve, sub-equilateral, rather 

 irregular, destitute of ligament and hinge teeth ; lower valve 

 attached, flat, sub-orbicular, with a muscular impression, com- 

 posed of two lunulate portions, meeting at one extremity, and 

 presenting the form of a horse- shoe ; upper valve conical, with 

 the apex inclined backwards, and the muscular impression mar- 

 ginal. — Obs. The earlier naturalists having only met with the 

 upper valve of these shells, placed them among the patelliform 

 univalves ; to some of which, particularly Pileopsis, they bear a 

 very strong resemblance. The species of Hipponyx are nume- 

 rous, and till lately only known in a fossil state. The recent 

 species belong to tropical climates : the fossil species are found in 

 the tertiary beds. Fig. 199, H. Cornucopia. 



HIPPOPODIUM. Conybeare. Fam. Cardiacea, Lam. — Bescr. 

 Equivalve, obliquely transverse, heavy, deep, inequilateral, um- 

 bones incurved ; ventral margin sinuated, so as to give a bilobed 

 appearance to the shell ; hinge incrassated, with one rugged 

 oblique tooth. — Obs. These fossils are found in the upper beds of 

 Lias. Fig. 129, H. Ponderosum. 



