OF MOLLUSCA. 25 



2. O. columellaris, Eydoux, t. 83 a. f. 3. 



3. O. Puelchana, t. 101. f. 1 ; t. 102. f. 1. 



4. O. Tehuelchana, t. 101.f.4; t. 102. f. 2; Adams, Gen. Moll. t. 15. 



f. 5. 



Olivella semistriata is found moving about by hundreds, with 

 great rapidity, in the wet sand in Panama (Cuming). Like other 

 species of the genus, the shells are often inhabited by Paguri. 



Olivella volutella is found in vast numbers over many acres on 

 the sandy beach west of the city of Panama ; most numerous 

 where the beach has a gentle slope midway between high and low 

 water mark. Some time after the retreat of the tide, it is found 

 crawling about with much vivacity on the wet sand. The shell, 

 while the animal is moving, is wholly covered with the mantle, 

 and the mantle is entirely concealed with a thick coat of sand. 

 When the first wave of the returning tide strikes them, washing off 

 their coat of sand, they instantly bury themselves. — Adams, Ann. 

 Lye. New York, 1852, 281. 



Has not the vesicular foot here been mistaken for the mantlet 



3. SCAPHULA. 



Shell ovate ; mouth expanded ; belt narrow. Frontal lobes of ani- 

 mal very large, rounded. Operculum distinct, half-ovate, nucleus 

 subapical. 



1. S. auricularia, t. 100. f. 1 ; t. 102. f. 6 ; Adams, Gen. Moll. t. 15. 

 f. 2. 



4. Agaronia. 



Shell ovate, acute ; mouth large, expanded ; front of pillar twisted 

 and cross-grooved ; belt double, wide. Frontal lobes of animal mode- 

 rate, acute. Operculum distinct. 



1. A. hiatula, t. 101. f. 4, 6, 7. 



2. A. megalostoma, Adams, Gen. Moll. t. 15. f. 3. 



b. Ancillarina. .Shell subcylindrical, polished; suture callous. 

 Mantle without any posterior beard; lateral teeth simple, 

 curved (fig, 12). 



-i: 



Shell more or less covered with an enamel coat ; outer lip often 

 with a tooth in front. 



1. Ancilla. 



Spire covered with an enamel coat, forming a narrow belt on the 

 penultimate whorl, not reaching to the hinder part of the mouth, 

 and leaving a naked space on the whorls ; axis imperforate ; outer 

 lip with a slight tooth. Operculum large, distinct, oblong, acute ; 

 nucleus subapical, near the front of the inner side. 



1. A. australis, t. 19. f. 5. 



