﻿PH1L0XENE. 237 



1810 and Onustus, Humphrey, 1797), and as having the wide umbilicus, flattened 

 shape, and smooth whorls of the Euomphali, and especially of the sub-genus 

 Straparollus, but bearing agglutinated bodies. This latter feature I have observed 

 in no less than three British species, although only slightly and occasionally in two 

 of them. As a matter of fact the external surface of these shells is often so injured 

 that slight agglutinations might easily be obscured ; but it seems certain that in 

 some instances there were agglutinations, and in other instances none. As, there- 

 fore, there appears to be no other character by which the shells bearing adherences 

 can be distinguished from the rest, we must conclude that (as is also the case in 

 German specimens) it is a habit only exercised by some individuals of the species 

 — perhaps only in cases where broken shells were handy to them. 



In the third species, on the other hand, the habit is constant, and the scars are 

 often so great as to affect the cast of the shell, and to show that the attached 

 fragments were sometimes very large. This species, which I had the pleasure of 

 showing Dr. Kayser in 1888 before the publication of his genus, is much larger 

 and more conical than Philoxene Isevis, and has a much smaller, though still large, 

 umbilicus. Hence it seems to necessitate some modification in the limits of the 

 genus, and we have therefore given its characters above. 



Kayser left X. Bouchardii, Desl., the first described Devonian "carrier" shell, 

 in the genus Xenojphora ; but it will be seen that one of the English species, 

 Ph. philosophus, comes so close to it that it can be distinguished only with some 

 difficulty. This shell, however, seems clearly to belong to Philoxene and not to 

 Xenophora, and therefore it seems probable that X. Bouchardii ought also to be 

 classed with Philoxene. 



The object of the agglutinations is supposed to have been for concealment ; 

 other possible causes might be for mere ornament, or to save the body of the 

 animal from jar. It is interesting to observe that these ancient " carriers " had 

 massive shells, whereas the Eocene and recent Xenophoridse have frequently very 

 thin or almost papyraceous tests. Hence it would appear that the agglutinations 

 in the latter case were probably for a different object — that of strengthening and 

 guarding the shell ; and it seems probable that the two groups had really no 

 connection with each other. Had they been lineally related, we should have 

 expected to find the thin shells among the ancient and the thick among the 

 modern forms, for the strain of carrying large masses of shell or stone ought 

 certainly to have tended to an ultimate thickening of the shell. That they are 

 unconnected is rendered all the more probable from the absence in the Devonian 

 shells of the fine characteristic ornament of many of the Phoridse, but never- 

 theless the general shape of the shells is so similar as to show that the family 

 of the Xenophoridse and the genus Euomphalus should probably be placed very 

 near together. 



