The Genus Xanno, Clarke. — Hyatf. 3 
described in a paper I am now preparing for publication. 
The type is Xarthecoceras [End.) o-assimphonatum (Whit- 
eaves sp.)* The only known species are this and Xarth. 
(End.) Simpson i\ sp. Billings. 
The youth of the specimens referred to above is in my 
opinion established by the aspect of the sheath. The sheath 
is complete in Clarke's figure 8 and approximately complete 
in the originals of figures 5, 7 and 2 and also 4. This is a 
most extraordinary fact considering the great variety of 
young specimens as a rule, and one might well claim that these 
were probably full grown. On the other hand the original of 
Clarke's figure 1, gives strong evidence in support of his con- 
clusion that the}^ are identical and belong to the same species. 
That they are each complete in their own stage is demonstra- 
ted by one of the specimens from Chatfield, figured here on 
plate I, figure 1. This is about the size and length of Clarke's 
figure 2 but is not a complete siphon like that specimen. It 
is a fragment of the apical end of some larger and older fos- 
sil. The sheath penetrating the center of the broken stem is 
represented by a narrow tube less than 2 mm. in diameter 
which at first seems to be an endosiphon. 
Having examined the tips of the siphon in Clarke's speci- 
mens of Xanno, I found on each a broken place or scar indi- 
cating in one specimen, the original of Clarke's figure 2, pos- 
sible contact with the external shell and having in the center 
what appeared to be the mark of an endosiphon. On each of 
the other specimens there were marks not wholly accounted for 
b}' abrasion, except in that of the original of figure 1, which 
is considerablj" worn. Suspecting that these indicated the 
presence of an endosiphon I ventured to make a section of 
the specimen described. 
radic tracfs of fibrous ilcpositioii in a specimrii of Emlot'erdH, E. protci- 
fiirrne''. from llif Troiitoii limestone Tlic filling varies from loose sub- 
crystalline or sparry to comparatively dense, opacpie, white with nu- 
mt^rous lines of de))osition, all of them parallel with the surfaces of the 
eiulocones. Tliese are crossed liere <ind there by curved lines which 
occasionally may have a fibrous aspect. Near the wall of Ihe siphon 
there is, in one spot, a number of tliese lines that may be described as 
indicating a tendency towards fibrillization in the slruclureof the fill- 
iuir. and in other parts there are similar ai»pearances especially near the 
wall of the siphon. 
*The Orthoceratidie of the Trt-nton limestone of the Winnipeg basin; 
Trans. Koval Sue. Canada, vol. i\. ]S!)1. 
