[maithewJ studies ON CAMBRIAN FAUNAS 41 



which the lower is rigid, especially in the median part of the ventral 

 side ; upper fifth of the tube thinner and more flexible. 



Sculpture. — The surface of the tube is marked by low, rounded 

 ridges of growth, which are directly transverse ; in the distal half there 

 are about three of these ridges in the space of a millimetre ; often the 

 tube appears smooth without, when the annulations are faintly marked 

 on the mould of the interior ; occasional more distinct annulations are 

 found at intervals along the tube. 



Size. — Width of the orifice, 3 mm, ; the tube can be traced at the 

 proximal end down to a diameter of |- mm. 



Horizon and Locality. — Upper Cambrian shales of Mount Stephen, 

 B. C. Infrequent. 



The chiten of the test in this species is peculiarly dense and firm, and 

 blacker than that of the trilobites with which it is associated ; in this 

 respect it reminds one of the graptolites of the Quebec group as seen at 

 Point Levis. It is evidently not a phosphatic shell, as it does not weather 

 to the bluish (lavender blue) colour found in Lingulellse and other 

 Brachiopods in which this salt (calcium phosphate) abounds. 



Urotheca parva, n. sp. (PL VII., fig. 2.) 



Small, narrow, cylindrical tube ; the larval portion thread-like, and 

 showing several diaphragms at the upper end where it changes into an 

 enlarged, thin, chitinous tube ; this is conical for one-quarter of its length, 

 and then becomes cylindrical. 



Sculpture. — Marked by exceedingly fine longitudinal and transverse 

 lines, giving a minutely cancellated surface. 



Size. — Length of the larval part of the tube, about 4 mm. ; length 

 of enlarged part, 10 mm. 



BYRONIA, n. gen. 



Among the rarer objects in the Mount Stephen shales are a few 

 examples of a tube worm of much larger size than Urotheca and which 

 is sufficiently distinct to form a new genus. This form also dwelt in a 

 horny tube, but thinner proportionately than that of the genus named, 

 the surface was marked by sharply raised annulations after the manner 

 of some Tentaculites, from which it diff'ered in having a sinuous, not 

 straight and rigid tube as in that genus. The proximal end (so far as 

 known) is a curved tube, one mm. in diameter, whence it gradually 

 enlarges to the orifice. 



It gives me much pleasure to couple with this genus the name of 

 Byron E. "Walkex-, Esq., of Toronto, to whom I am indebted for the 

 opportunity of examining the fossils of Mount Stephen. 



