Cretaceous Fossils from British Columbia. 31$ 



well preserved cast of the interior of nearly the whole of 

 the prolonged and reflected portions of the shell, with 

 small pieces of the test remaining. Its maximum length 

 is a little more than live inches and its marginal outline 

 is regularly but rather broadly elliptical, as the shell is 

 curved obliquely outward before becoming straight and 

 prolonged. The distance between the prolonged and 

 reflected portions is much less than the dorso-ventral 

 diameter of the reflected portion. The surface is strongly 

 ribbed, and many of the ribs bear a large conical 

 tubercle on each side of the periphery, but there is much 

 irregularity in the disposition of the ribs and tubercles. 

 On the sides of the shell the ribs are usually simple and 

 disposed with comparative regularity, but they occasionally 

 bifurcate, or a short rib is intercalated between two longer 

 ones, and two ribs frequently coalesce on both sides, at 

 one of the tubercles on the outer margin of the periphery. 

 In some places a single continuous rib devoid of tubercles 

 alternates with a single tuberculated rib or with two ribs 

 that bear a tubercle between them on each side of the peri- 

 phery, but the pairs of tubercles are placed at varying dis- 

 tances apart longitudinally, and not rarely a little to one 

 side of a rib rather than immediately upon it. The sutural 

 line is nowhere visible. 



The specimen figured, which is slightly distorted, is 

 nearly eight inches in its maximum length. Although 

 imperfect posteriorly, enough of the earlier portion of the 

 shell is preserved to show that it is narrowly elongated, 

 sinuous, spirally twisted and curved obliquely outward 

 before becoming straight and prolonged, and that it does 

 not consist of a straight shelly tube bent twice or more 

 upon itself, as in Hamites proper. The spiral twist pos- 

 teriorly is especially marked by the lateral position of the 

 two rows of tubercles which ultimately border the peri- 

 phery. The ribs, which sometimes trifurcate, are much 

 narrower than the broad concave grooves between them, 



