17 



CHAPTEE III. 



DESCRIPTION OF UNIVALVE SHELLS. 



PTERONOTUS festivus, Hds., Fig. 1, PL 

 II, is a representative of the great family 

 of the Muricidae or Rock Shells, which abound 

 in the warm waters around Panama, and furnish 

 so many parlor ornaments. Most of the family 

 have very rough exteriors, and are smooth and 

 brilliantly tinted within. This species is about 

 an inch and a half in length, irregularly spindle- 

 shaped, i. e. tapering toward both ends, with large, 

 reflexed frills, and a tubular canal. Color, 

 whitish, with various dark markings. It is 

 found chiefly in the southern part of the State. 



Ranella California*, Hds., Frog Shell, Fig. 2, 

 PI. II, sometimes glows to a length of six inches. 

 It is a solid, light colored shell, with two heavy 

 folds on opposite sides, long canal, the edge of 

 the aperture crenulated ; spire of about four 

 whorles. Common length, three inches. 



Chrysodomus dirus, II ve., Golden Spindle- 

 Shell, Fig. 3, PI. II, has an ominous name, but the 

 only ill luck we ever experienced while gathering 

 theso shells was getting caught by the tide on Dux- 

 bury Reef, at Bolinas, and being obliged to wade 

 ashore. It is spindle shaped, from one to two 



