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



Fig. 1. 



/'A 



the valves which are seen in the interior of the tnbe in Asper- 

 gilla. 



This shell must form a distinct genus, which I have named 

 Humphreyia, after George Humphrey, the shell-dealer and con- 

 chologist, who published the Catalogue of M. De Calonne's 

 collection, in 1797 ; and I have no doubt it is the type of a new 

 family, Humphreyiadce. 



The two specimens in Mr. Cuming's collection which are here 

 figured (figs. 1 & 2), are very unlike ; and this difference has 

 assisted me in giving the above 

 account of their structure and 

 formation. 



In the larger one (fig. 1) the 

 valves of the shell were consider- 

 ably enlarged and well developed, 

 approaching the form of ordi- 

 nary bivalve shells, before the 

 animal developed the slipper-like 

 case by which they are attached, 

 and began to develope the 

 hinder tube. In the other spe- 

 cimen (fig. 2), on the contrary, 

 the shelly valves are scarcely 

 more developed than they were 

 on the newly-hatched animal, 

 which appears to have proceeded 

 at once, as soon as it came into 

 the world, to form the bag- like 

 cavity over the gape in front 

 and between the ventral edge of 

 the valve, to attach itself to the rock, and to proceed to develope 

 its tube. 



It may be observed, though we are not able to assert it posi- 

 tively (as there are only two examples known), that the difference 

 between the two specimens depends on the kind of place to which 

 the animals were attached: the larger one was attached to a 

 mussel-shell, and the other to a piece of rough sandstone rock. 



I was glad to see, on consulting Mr. A. Adams's description 

 of this shell, for the purpose of quoting his name and figure, 

 that he had observed this peculiarity, and agrees with me as to 

 the manner in which the tube is formed. He observes : " The 

 fact of the tube being nothing more than the valves greatly 

 expanded and modified, is well shown in one of the specimens/' 

 (P. Z. S. 1852, 91.) It does not appear whether Mr. A. Adams 

 considered this formation of the tube as a peculiarity of the 

 species, or as explaining the development of the tube of Asper- 



Humphreyia Strangei. 



