Remarks on the Trilohite. 27 



In further illustration of this subject, we here add, with some 

 slight alterations, from Dr, Bucklaiid's admirable Bridgewater 

 treatise, a considerable part of his section on the trilobites, which 

 exhibits in a very condensed form the facts and opinions which 

 have any bearing on this inquiry. I have greater satisfaction and 

 more confidence in referring to his remarks, than in attempting 

 to offer any thing of a similar nature drawn up by myself After 

 mentioning that the serolis is the nearest approach among living 

 animals to the external form of trilobites, he adds, the next ^^ ap- 

 proximation to the character of trilobites occurs in the limulus or 

 king crab,* a genus now most abundant in the seas of warm cli- 

 mates, chiefly in th^se of India, and of the coasts of America. 

 The history of this genus is important, on account of its relation 

 both to the existing and extinct forms of crustaceans ; in it there 

 are but slight traces of antennae, and the shield which covers the 

 anterior portion of the body, is expanded entirely over a series of 

 crustaceous legs. Beneath the second, or abdominal portion of 

 the shell, is placed a series of thin, horny, transverse plates, sup- 

 porting the fibres of the branchiae, and at the same time acting as 

 paddles for swimming. The same disposition of laminated bran- 

 chiae is found also in the serolis. Thus while the serolis presents 

 a union of antennae and crustaceous legs, with soft paddles bear- 



in 



;position 



legs and paddles, and only slight traces of antenna5 ; in the bran- 

 chipus we find antennae, but no crustaceous legs ; while the tri- 

 lobite being without antennae and having all its legs represented 

 by soft paddles, is by the latter condition placed near branchipus 



* In my boyhood I was very familiar with the habits of this crustaceaiij called in 

 the northern States, horse fish — or horse shoe fish, from its furm. 



On the fine hard sea beach at Fairfield in Conaecticut, I was in the habit of 

 taking these animals in great numbers, for the purpose of feeding darks : tlie ova 

 being very abundant, and being greedily devoured by tlie young ducks, after the 

 shell of the animal is crushed or cut open. Their fecundity must have been very 

 great, since a large individual female, (the horizontal diameter of whose shell 

 mif^ht have been nine or ten inches,) afforded several gills of spawn. The habit 

 of these animals is to come in with ilie rising tide, and to walk on the bottom, aa- 

 cendinff the shelving beach, until they arrive in shallow water. The pellucid sea 

 at Fairfield, rippling over siliceous sand, enabled me and my puerile compan- 

 ions to see them through the waves, and by wading we easily secured them by 

 seizing the spike or tail, their motion being too slow to admit of their escape. 

 Hundreds of them might have been caught at a single tide, of every size from 

 nearly a foot in diameter to an inch ur less— these infants having also the power of 

 travelling on the bottom. — Sen. Ed. 



