16 Dr. J. E. Gray on the Structure of Humphreyia. 



axis are marked by peculiar furrows, — characters not exhibited 

 by the present species. The transverse furrow on the head- 

 shield probably corresponds more or less in outline with the 

 underlying hypostoma; J)ut no traces of the latter organ, as 

 already remarked, have yet been found. 



In the preceding article on Asaphus Canadensis, it was stated 

 that Professor Hall had published, in the first volume of the 

 ' Palaeontology of New York/ two imperfect caudal shields, 

 under the name of Asaphus (?) latimarginatus. I would willingly 

 adopt this specific name for our second Canadian form, because, 

 so far as it is possible to determine, the two may prove eventually 

 to be alike; but, on due consideration, I have thought it ad- 

 visable to bestow upon the form in question a name altogether 

 distinct. My object in this is solely to avoid the chance of con- 

 fusion, in case the thorax and head-shield of Professor Hall's 

 form should hereafter be discovered, and be found on examina- 

 tion, as would very likely happen, to constitute a different spe- 

 cies. I therefore claim the privilege of naming the Trilobite 

 described in this article, — a privilege to which I am justly en- 

 titled by the really indefinite character of the figures referred to 

 above. The name I adopt as the most appropriate, under the 

 circumstances of the case, is that of Asaphus Halli. Palaeonto- 

 logists, I am sure, will receive it willingly. 



III. — On the Structure of Humphreyia, an anomalous Bivalve 

 Shell, hitherto confounded with Aspergillum. By Dr. J. E. 

 Gray, F.R.S., V.P.Z.S. &c. 



In the preceding Number of this Journal, I gave an account of 

 the development of the genus Aspergillum. Shortly after it was 

 in print, Mr. Cuming kindly allowed me to examine the speci- 

 mens of that genus in his extensive collections. I was delighted 

 to find, mixed with the other species, a shell, which I was con- 

 vinced, on a very cursory glance, could not be formed in the 

 same manner as the Aspergilla, and, indeed, could have but very 

 little relation to the other species of the genus to which it has 

 been referred by Mr. Arthur Adams, who described and figured 

 it in the ' Proceedings of the Zoological Society ' for 1852 (p. 91. 

 t. 15. f. 3), under the name of Aspergillum Strangei. It was 

 received from Sydney Bay, Australia, by the late Mr. Strange. 



This animal, instead of living in a tube sunk in the sand or 

 mud of the sea-coast, like the Aspergilla, or in a tube more or 

 less immersed in the substance of shells, rocks, or other marine 

 bodies, like the Gastrochcence and Clavagellce, fixes itself by its 

 ventral surface to shells or rocks, so that the whole of the 



