Dr. F. A. Bather— The Mount Torlease Annelid. 539' 



from which perhaps a little should be deducted for the flattening. 

 At the smaller end the outside diameter is 1-6 mm. The thickness 

 of the tube-wall at the larger end is not less than '3 mm. ; at the 

 smaller end it was rather thinner. It is doubtful whether the 

 transverse section was cii-cular: it may have been slightly polygonal. 

 The inner wall of the tube is smooth, but the outer wall was covered 

 with about fourteen slight but distinct longitudinal ribs (Fig. 4&), 

 These are almost or entirely worn away from the exposed surfaces, 

 but are seen in section, and often on the impressed portions of the 

 outer wall. 



The three fragments preserved in specimen 23 all appear to have 

 belonged to individuals rather larger than those in No. 22. They 

 are much worn, and the tubes appear to have been filled with 

 a greenish chalcedony rather than with shale. The ribs are shown 

 in each of them, and very plainly in the largest, where three of them 

 occupy a width of 1'2 mm. (Fig. 76). 



Of this form also, the systematic position is not free from doubt. 

 Hitherto it has generally been regarded as the tube of an annelid, 

 but to this there are certain objections. The shell, for instance, 

 seems rather too stout and too regularly curved. Its general shape 

 reminds one of Cornulites, to which Captain Hutton referred some 

 tubular fossil (loc. cit. supra), but it is ribbed, not annulate. If an 

 annelid it would be suggestive of a far later age than that to which, 

 stratigraphical evidence would assign it. Short, curved annelid 

 tubes with longitudinal ribs do not seem to occur before the Lias, 

 in which epoch there lived "Serpula" quinquecristata, Goldf., 

 " aS." tetragona, J. de C. Sow., and S. quadrilatera. Serpula 

 heptagona, Sow., from the Barton Beds of the Upper Eocene, is 

 a similar form. But the most suggestive are the tubes from the 

 Maestrichtian Chalk, now referred to Denis de Montfort's rather 

 problematical genus Fyrgopolon (1808), e.g. F. deforme (Lam.) and 

 P. ciplyana, Kyckholt. But none of these real or supposed annelid 

 tubes has the same regularity of shape as appears to have been 

 possessed by the present fossil. And if not an annelid, the conclusion 

 is inevitable that it is the shell of a Scaphopod, probably of the 

 genus Dentalium (sens. lat.). Since that genus, or some close ally 

 thereof, has persisted from Devonian times to the present, this 

 conclusion, while throwing no fresh light on the age of the rocks, 

 is at least in harmony with other evidence. Several species of 

 Dentalium or its subgenus Entalis have been recorded from Carboni- 

 ferous rocks. Since the habitat of Dentalium is in marine mud, this 

 conclusion further agrees with the evidence afforded by Torlessia. 

 The fact that the stereom has been converted into silica renders 

 inapplicable the argument from its arragonite or calcite constitution, 

 and also prevents the investigation of its microscopic structure. 



The tubes show no trace of slits at either end, so that it is 

 legitimate to leave them in the genus Dentalium, even as now 

 restricted (see Simroth, 1895, p. 458). Among the species of 

 Dentalium (sens, lat.), both recent and fossil, the one to which the 

 present form seems to bear most resemblance is D. formosum, Adams 



