274 MANUAL OF THE MOLLUSCA. 
Norway, North Britain, Tierra-del-Fuego. In 20—100 fathoms 
water. 
Fossil, in the glacial formations of North Britain. 
RIMULA, Defrance. 
Etymology, diminutive of rima, a fissure. 
Synonym, Rimularia. 
Recent type, R. Blainyillu, Pl. XI., Fig. 4. 
Shell thin and cancellated, with a perforation near the anterior 
margin. 
Distribution, several species found on sandy mud at low water, 
or dredged in from 10—25 fathoms. Philippines (Cuming). 
Fossil, 3 species. Bath oolite—coralrag. Britain and France. 
EMARGINULA, Lam. 
Etymology, diminutive of emarginata, notched. 
Type, li. reticula, Pl. XI., Figs. 5 and 6. 
Shell oval, conical, elevated, with the apexrecurved; surface 
cancellated ; anterior margin notched. Muscular impression 
with recurved points. The nucleus (or shell of the fry) is spiral, 
and resembles scisswrella. The anterior slit is yery variable in 
extent. The animal of emarginula (and also of punctwrella) has 
an isolated cirrus on the back of the foot, perhaps representing 
the operculigerous lobe. (Forbes.) Lingual dentition, median 
teeth sub-quadrate ; laterals 4, oblong, imbricated ; uncini about 
60, the first large and thick, with a lobed hook, the rest linear, 
with serrulated hooks. (Loyén.) 
Distribution, 40 species. West Indies, Britain, Norway, 
Philippines, Australia. Range from low water to 90 fathoms. 
Fossil, 40 species. Trias—. Britain and France. 
Sub-genus. Hemitoma, Sw. 
Type, EK. octoradiata (E. rugosa, Pl. XI., Figs. 7 and 8). 
Shell depressed, anterior margin slightly channeled. 
PARMOPHORUS, Blainyille. Duck’s-bill limpet. 
Etymology, parme, a shield, and phoreus, a bearer. 
Type, P. australis, Pl. XI1., Fig. 9. 
Synonym, Scutus, Montf. : 
Shell lengthened-oblong, depressed; apex posterior; front 
margin arched. Muscular impression horse-shoe shaped, elon- 
gated. The shell is smooth and white, and permanently covered 
by the reflected borders of the mantle. The animal is black, 
and very large compared with the shell; its sides are fringed 
with short cirri, and its eyes sessile on the outer bases of thick 
