268 THE HORSE FOOT CRAB. 
forward shield. But Limulus and Eurypterus have both 
two large sessile Ap set high up on the shield, and two 
ocelli set forwar 
The want of an L'iitiodlatéd tail was soon apparent in the 
case of our little Limulus. ‘The slightest obstacle turns it 
on its back, when, not having this organ, which the adult 
uses so effectively in such emergency, the little thing begins 
a vigorous flapping of the branchial plates. This causes it 
to rise in the water; then by ceasing the agitation it at once 
descends, with a chance of alighting right side up. Should 
it miss the ascent would be repeated until its desire was 
accomplished. 
August 15th.—Eighty-two days from the spawning. A 
great many had hatched, and many had perished for want 
_ of care. I had almost given exclusive attention to the one 
described above. It had its second moult to-day. A few 
minutes sufficed for it to withdraw itself from its baby suit. 
I noticed that it stopped a little while, as if to rest, having 
the caudal appendage only half withdrawn from the old 
shell (Pl. 3, Fig. 11). At last out it came, a person of dis- 
tinction possessing the articulated rapier. It is a true Limu- 
lus now, and fully entitled to carry for life, the sword of 
honor, which has ever been the family mark of rank. The 
animal is now quite a fourth of an inch in width, and its tail 
is the one-twentieth of an inch in length. Where did it keep 
it while in the old dress? It must have been bent under and 
upon the abdomen. I have noticed them since at this 
moult, with the tail considerably incurved, and which re- 
quired some hours to straighten out.  Dorsally the little 
thing has now nearly the complete appearance of the adult 
Limulus. The setaceous fringe of the abdominal carapace 
had disappeared, and had left an, armature of teat-like or 
half-developed spines; and the spiny fringe of the cephalic 
shield was quite gone. The posterior projections of this 
shield are now sharp. The tail is distinctly articulated, but 
somewhat stumpy. A section of the adult tail would be al- 
