212 



EVENINGS AT THE MICEOSCOPE. 



tlier than by referring to the figure. When they first 

 escape they rarely exceed half a line in length. The 

 body is ovoid, the dorsal shield large and inflated ; on 

 its upper edge and about the middle is a long spine, 

 curved posteriorly, and rather longer than the diameter 

 of the body, though it varies in length in difi'erent spe- 

 cimens ; it is hollow, and the blood may be seen circu- 

 lating through it. The upper portion of the body is 



ZOEA OF SnOEE-CRAB. 



sap-green, and the lower semi-transparent. The eyes 

 are large, sessile, and situated in front, and the circum- 

 ference of the pupil is marked with radiating lines. The 

 lower margin of the shield is waved, and at its posterior 

 and lateral margin is a pair of natatory feet. The tail 

 is extended, longer than the diameter of the shield ; and 

 is composed of five equal annulations, besides the ter- 

 minal one ; its extremity is forked, and the external 



