MUSEUM OF COMPARATIVE ZOOLOGY. 197 



by accident in the vacant carapace of the Trilobite before its petri- 

 faction. 



1846. Prof. Beyrich presented the account of the discovery of the 

 intestinal canal of Trinucleus. This was fully corroborated by M. 

 Barrande, and more recently by Dr. Volborth. 



1863. Dr. Volborth discovered the intestinal canal of an lllcenus. 

 It was constricted, so as to appear to be an articulated organ. 



1870. Mr. E. Billings. This discovery is mentioned on a pre- 

 ceding page. 



. Mr. Henry Woodward mentions the discovery of the jointed 



palpus and one of the maxilla? of an Asaphus, in position by the side 

 of the hypostoma. 



1876. Mr. C. D. Walcott announced the discovery of the natatory 

 and branchial appendages of the Trilobites. 



1877. Mr. C. D. Walcott. Additional evidence is given to show 

 the presence of manducatory jaws, ambulatory legs, and branchiae, in 

 the genera Calymene and Ceraurus. 



The discovery by M. Eichwald of an isolated crustacean (?) leg, il- 

 lustrated on Plate VI. fig. 4 of this paper, is an instance of discoveries 

 mentioned by M. Barrande as having little value. Mr. Billings first 

 discovered evidence of the presence of ambulatory legs in the Trilobite, 

 and this was so far from satisfactory that Messrs. Dana, Verrill, and 

 Smith pronounced the so-called legs not to be such,* and the discovery 

 has been entirely ignored by many recent authors in zoology, as not 

 having any bearing on the question of the zoological position of the 

 Trilobite. Others, however, have accepted it, as has been mentioned. 



The discoveries of the writer have been received in about the same 

 manner. So many times the discovery of the feet and other organs 

 of the Trilobite had been announced, and subsequently proved to have 

 been based on insufficient evidence, or no evidence at all, that natu- 

 ralists were disinclined to accept any statement that such discoveries 

 had been made, without absolute proof of their genuineness. 



From the illustration given by Mr. Billings of the Canadian speci- 

 men of Asaphus, and an examination of a cast of the original, I cannot 

 but think that the remains are what he considered them to be. Al- 

 though the specimen does not reveal the structure of the Trilobite as 

 we now know it, it is the first that gave any positive information of the 

 presence of jointed legs beneath the thorax of the Trilobite. 



* Amer. Journ. Scien. and Arts, 3d series, I. 320, 1871. 



