THE DACTYLE PHOLAS. 331 



General description. 



THE PHOLAS. 



THE animal herein contained is called an 

 ascidia, and has a shell of two valves, that open 

 widely at each end, with several lesser ones at 

 the hinge. The hinges are folded hack, and 

 united by a cartilage; and in the inside, beneath 

 the hinge, there is an incurved tooth. 



The pholades perforate clay, spongy stones, 

 and wood, while very young ; and, as they in- 

 crease in size, they enlarge their habitation 

 within, and thus become imprisoned. They are 

 always found below high-water mark, and a 

 mass of rock may sometimes be seen wholly 

 perforated by them. They have two orifices or 

 openings capable of elongation in the manner of 

 a proboscis ; one of these is supposed to be the 

 mouth, and has the faculty of spouting water. 

 Most of them contain a phosphorescent liquor, 

 of great brilliancy in the dark, which also illu- 

 minates whatever it touches or happens to fall 

 upon. 



THE DACTYLE PHOLAS. 



THIS species has an oblong shell, marked 

 with somewhat spinous stripes. When full grown 

 it is about an inch and a quarter long, and near 

 five inches broad. It is of a whitish color, and, 

 2 T 2 



