PISIDIUM.—AURICULA. 505 
that given by Prime ?; Binney’s figure in the second edition of A. Gould’s ‘ Report of 
the Invertebrata of Massachusetts,’ p. 113, fig. 125, is a copy of that given by Prime. 
Similar small shells were collected by B. Biolley at San José, Central Costa Rica, 
1135 metres above the sea. 
2. Pisidium singleyi. 
Pisidium singleyi, Sterki, Nautilus, xi. p. 112 (1898)'. 
In shape and colour resembling P. punctatum; the surface very finely, almost regularly striated, somewhat 
shining ; interior surface with fine but well-marked crowded pits, visible from the outside; hinge rather 
fine. 
Long. 3°3, alt. 2°8, diam. 2°4 millim. 
Hab. N.W. Mexico: Itzlan Creek, Guadalajara!. Also in the Guadaloupe River, 
Texas !. 
C. SPECIES SUBMARINA*. 
Under this heading I place the Mollusca that live on or near the sea-shore; their 
chief haunts are the mangrove-swamps (Auriculide, Potamides, and some Littorine), 
or the rocks near and above high-water mark (some Auriculide and Littorine). 
Fam. AURICULIDA. 
Air-breathing Gastropods with only two feelers, the eyes at or behind their base ; 
sexes united; radula with numerous teeth, somewhat like those of the Helicide, but 
in waved transverse rows. An outer shell, protecting the whole animal; no operculum. 
Shell spiral, solid; aperture longitudinal, its margins mostly thickened and often 
provided with teeth or plaits; a columellar plait (fold) always present at the base of 
the wall of the aperture, opposite the outer margin. 
‘The species of this family are characteristic submarine forms, most of them (the 
genus Carychium and some others excepted) living in estuaries or in places reached by 
the tide. 
AURICULA. 
Auricula, Lamarck, in Mém. Soc. @’Hist. Nat. de Paris, 1799, p. 76; Syst. des Animaux sans 
Vert. p. 92 (1801) ; Pfeiffer, Monogr. Auric. p. 123; Catal. Auric. Brit. Mus. p. 93; 
v. Martens, in M. Weber’s Zoologische Ergebnisse einer Reise in Niederlandisch Ostindien, 
iv. pp. 149, 150 (1897) (part.). 
Auriculus, Montfort (1810) ; Pfeiffer (1376). 
Ellobium, C. Botten (1798); H. & A. Adams, Gen. Rec. Moll. p. 237 (1858). 
* See pp. 1, 353. 
70* 
