CEABS AND SHEIMPS. 213 



angles are long, slender, pointed, and attached to the 

 last annulation by joints. Between the external angles, 

 and on each side of the median line, are three lesser 

 spines, also attached to the last ring by joints. Between 

 the eyes, and from near the edge of the shield, hangs a 

 long, stout, and somewhat compressed appendage, 

 which, as the animal moves, is reflexed posteriorly be- 

 tween the claws. Under each eye is another append- 

 age, shorter, and slightly more compressed. The claws 

 are in three pairs ; each is composed of three joints, and 

 terminates in four long, slender, hair-like appendages. 

 These claws are generally bent on the body, but stand 

 in relief from it. If the animal be viewed in front, the 

 lower margin of the dorsal shield will be found to be 

 waved into three semicircular festoons, the two external 

 of which are occupied by the eyes, and between which 

 the middle one intervenes ; the general direction of the 

 claws will be seen to be at right angles to the body. As 

 the young lies inclosed within the membranes of the 

 egg, the claws are folded on each other, and the tail is 

 flexed on them so far as the margin of the shield, and, 

 if long enough, is reflected over the front of the shield 

 between the eyes. The dorsal spine is bent backwards, 

 and lies in contact with the dorsal shield ; for the young, 

 when it escapes from the egg, is quite soft, but it rapidly 

 hardens and solidifles by the deposition of calcareous 

 matter in what may be called its skin. The progress of 

 this solidification may be very beautifully observed by 

 watching the circulation in the doral spine. When the 

 creature has just effected its liberation from the egg, 

 the blood-globules may be seen ascending to the apex ; 

 but as the consolidation advances, the circulation be- 

 comes more and more limited in its extent, and is finally 



