338 
Oìi thè genus Ponijgholyx and its Allies, 
The odontophore is about four times as long as it is wide. 
It is broadly reflexed at its anterior extremity, and thè sur- 
face is moderately convex. 
The teeth are transverse in a line almost straight. The for- 
mala is 22 — 1 — 22, or fortj-five teeth in a row, and there are 
about one hundred and fiftj rows. 
The centrai tooth is nearly twice as long as it is broad. The 
cusp is half as long as thè base, and bifid or furnished with two 
minate pointed teeth at thè posterior extremity, and occasion- 
ally two prominent tubercles on thè base. The inner laterals 
are irmeli wider than thè centrai tooth, and thè cnsps are nearly 
twice as long as thè bases. They are rounded-rhomboidal 
and slightly indented, having a trilobate appearance. 
The decrease in width and thè lobed appearance become 
more evident toward thè margin of thè odontophore. The cnsps 
of thè outer live rows are very mudi compressed, and hence 
have a tridentate rather than a trilobed appearance. 
While thè teeth appear to be of a pnrely ehitinous consis- 
tency, and are quite insoluble in caiistic potash, thè bnccal 
piate is liable to destruction from cont'inued boiling in a con- 
centrated solution. 
OirGulatory sysUm. The heart is small and occupies a posi- 
tion midway between thè buccal mass and thè stomach, and 
laterally is between thè oesophagus and thè descending intes- 
tine. One Principal blood-vessel snpplies thè liver and adja- 
cent viseera, and another thè buccal region, thè tentacles, and 
thè head. A small brandi accompanies thè ovarian duct and 
accompanying glands, wdiile another snpplies thè stomach. 
Reproductive System. The ovarian duct, or vagina, opens 
into thè pulmonary chamber, dose by thè anns and just within 
thè maiitle margin. A small sac, thè “ genital bladder” of 
Leidy, is situated near thè end of thè vagina. Behind this, thè 
ovidiiet is dilated, forming a fossa corresponding to thè uterus. 
Further back a gland opens into thè oviduct, beyond which thè 
lattei’ is again somewhat lobed and dilated. The ovary is 
