EXPLANATION OF PLATES. 369 
Lb. Labia, lips: 7. inferius, under lip; f. fimbriatum, fringed lip ; 
s. superius, upper lip. 
Lt. Latera, sides. 
In. Lingua, tongue. 
M. Musculus, muscle: a.a. musculus adductorius anticus, anterior 
closing muscle ; @.p. musculus adductorius posticus, posterior 
closmg muscle; o. musculus orbicularis, orbicular muscle ; 
0. a.j. musculorum orbicularium junctio antica, anterior junction 
of the orbicular muscles; 0.p.j. musculorum orbicularium junctio 
postica, posterior junction of the orbicular muscles; s. a. mus- 
culi longitudinales abdomen suspendentes et pedem retrahentes, 
longitudial muscles supporting the abdomen and retracting 
the foot; a.a.7. musculi adductoris antici impressio, impression 
of the anterior closing muscle; a. p.7. musculi adductoris postici 
impressio, impression of posterior closmg muscle ; tr. r.7. mus- 
euli tracheas retrahentis impressio, impression of the muscle 
which withdraws the trachee. 
Mn. Mandibule, jaws. 
Mr. Margo, margin: a. anterior; 7. inferior; p. posterior; s. su- 
perior. 
O. Ovarium, ovary. 
Qc. Oculus, eye. 
Op. Operculum, opercule or lid. 
Os. Os, mouth. 
P. Pes, foot. 
Pe. Pericardium, the cavity which contains the heart. _ 
Pl. Pallium, mantle: dz. lobus dexter, right lobe; sn. lobus sinister 
left lobe ; 7. a. junctio antica, the anterior junction ; 7. p. junctia 
postica, the posterior junction. 
Pt. Peritrema, peritreme ; the hard secretion on the borders of the 
univalve shells, from the part from which the animal issues. 
R. Regio, region; the situation of any part. 
T. Testa: a. aspectus, aspect; dz. dexter, right; 7. mferior; sm. 
sinister, left; s. superior; a. teste accessorize, supplementary 
shells; ap. apex, point; 6. basis, bottom or base; v. valve, 
valves; dz. dextra, right; sz. sinistra, left valve; uw. umbones ; 
en. cuniculus, syphon or groove. 
Tn. Tentacula, tentacles; s. superiora, superior; 7. inferiora, infe- 
rior; dx. dextra, right; sn. sinistra, left tentacles. 
Tr. Trachez, respiratory tubes: 7. inferior; s. superior. 
V1. Valve, valves: uw. umbilicus, navel. 
