Dr. F. A. Bather — Tube-building Fossil Annelides. 551 



' Innenbau ' (to use the expressions of Ehlers), one would expect to 

 find more evidence of the fact in so large a collection. The second 

 explanation presents no serious difficulty, but its correctness could 

 only be estimated by the person who actually found the specimen in 

 the chalk-pit. 



It appears, then, that the reference of the naked tubes to Terebella 

 lewesiensis rests on quite inadequate proof. Closer examination of 

 these fossils will show that they have characters of their own quite 

 distinct from those of any of the protected tubes. 



Although, as every collector of Chalk fossils knows, these naked 

 tubes, or tube-infillings, are quite common, yet there are not many in 

 the national collection. This may, indeed, be due to their verv 

 commonness, as well as to the fact that they are generally dismissed 

 as indeterminable ' fucoids '. The following are the only localities 

 and horizons represented : — 



Betckworth, Surrey. Albian, Upper Greensand. [A 1638.] 



Wetton Vale, Louth, Lincolnshire. Cenomanian, subglobosus zone, Tottern- 



hoe Stone. [A 1639.] 

 Glynde, Sussex. Cenomanian, ? subglobosus zone. [58253.] 

 Cowslip Pit, near Guildford, Surrey. Cenomanian, ? subglobosus zone. 



[A 1574-A 1577, A 1582.] 



It is clear that none of these specimens is complete. The greatest 

 length attained is 19 cm. [A. 1574]. 



Some of the specimens are fairly straight. This might be expected 

 in the shorter lengths, but it is also rather notably the case in A 1638, 

 with a length of 16*5 cm. Others are bent or slightly sinuous; thus' 

 58253 is bent into two limbs, 5'5 and 6 cm. long, and has a length of 

 10 cm. along the chord. 



In diameter there is not much difference between different parts of 

 the tube, but A 1576 tapers slightly. The section when clearly seen 

 is elliptical, and in the following list both diameters are given : 10 and 

 5mm. [A 1582, A 1575]; 15 and 12 mm. [58253]; 15 mm. [A 1574]; 

 17 mm. [A 1639]; 17 and 12 mm. [A 1577]; 20 mm. [A 1576]; 

 20 and 17 mm. [A 1638]. The last specimen is from the Upper 

 Greensand, so that, so far as the Cenomanian specimens are concerned, 

 it is clear that their normal maximum diameter is considerably less 

 than that of the fish-debris and plant-debris tubes. 



The surface-ornament of these tubes, though faint and often obscure, 

 seems to be of definite character. It may be roughly described as 

 cancellate, since the surface, if viewed from a distance under oblique 

 lighting, shows a number of slight depressions arranged in fairly 

 regular transverse and longitudinal rows. Closer examination suggests 

 that the appearance is due to a system of transverse folds or waves, 

 crossed by larger and less regular longitudinal folds. Both systems 

 of folds are clearly seen in 58253, A 1638, and rather less clearly in 

 A 1582. The longitudinal folds are particularly clear in A 1574 (Fig. 5). 

 The transverse folds are seen plainly in A 1577 and A 1576, and less 

 plainly in A 1575 ; in these and in most other cases where they are 

 observed the transverse folds seem to run in curves, forming a succession 

 of widely open V's (Fig. 4). In A 1639, however, from the Totternhoe 

 Stone, the transverse folds, so far as seen, go almost straight round the 



