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



by crushing, especially in the larger specimens. In the following 

 cases the maximum width observed is the one given. Beginning with 

 10 mm. (3 specimens), this maximum passes through 13 mm. (1), 

 14 mm. (1), 15 mm. (3), 16 mm. (3), 17 mm. (2), 18 mm. (4), 

 20 mm. (13), 21 mm. (1), 22 mm. (3), 23 mm. (1), 25 mm. (2), 

 28 mm. (1), 30 mm. (4), up to 35 mm. (4): total, 46 specimens. 

 It will be observed that by far the largest number of specimens is 

 associated with the width of 20 mm., and that there are 17 specimens 

 below this and 16 above it. Making allowance for the exaggeration 

 by crushing in the widest specimens, we infer that this width of 

 20 mm. is almost exactly the mean, and that the natural limits of the 

 species are about 10 mm. and 30 mm. In the circumstances one 

 would perhaps not expect any relation between the length of the 

 specimens and their width ; certainly no such relation is perceptible. 

 Neither is there any relation between the width of the specimens and 

 the horizon from which they come. 



A specimen from the Gault, though also composed of fish-remains, 

 differs from all the Chalk specimens in its markedly greater width. 

 Since there is no reason for regarding this as due to exceptional 

 crushing or any peculiar conditions of preservation, and since it is 

 improbable that a species living in Gault mud continued unchanged 

 into the Chalk ooze, it seems advisable to establish a new species — 



' Terebella'' lutensis 1 , n.sp. 



Diagnosis. — Tube of fish-debris, with diameter over 4 cm. and with 

 a possible length of 29 cm. or more. 



Horizon. — Albian: Gault. 



Locality. — Eastbourne, Sussex, so far as recorded. 



Holottjpe.— Brit. Mus. A 23, ex Coll. John Morris. (Plate XXIV, 

 Tig- 6.) 



The exact measurements of the holotype are 29 cm. X 4'5 cm. X 

 2*4 cm. The wall is thick and has a coarse appearance, due to the 

 large size of the scales and bone-fragments and their irregular 

 arrangement. 



Tubes of Plant-debris. 



Of these there are in the British Museum seven specimens. Two 

 of them [A 1565, A 1566] from " Dorking Pit", Surrey, are probably 

 of Cenomanian age from the zone of Jlolaster subglolosus ; one 

 [A 1640] is from the "Upper Chalk" of Broadstairs, Kent; of the 

 others [A 1567 -A 1570] from the Chalk, probably of Sussex, the 

 precise localities and horizons are unknown. 



There can be no question but that these bodies are of the same 

 nature as the tubes made of fish-debris, and many of the remarks 

 concerning those are equally applicable to these specimens. None of 

 them, however, exceeds 16 cm. in length [A 1640]. The widths 

 range from 17 to 35 mm. Reference has already been made to 

 A 1567, which has apparently a slight branch ; the tube is 7"5 cm. 

 long, 23 mm. wide at one end, and only 1 1 mm. wide beyond the 

 apparent branch — measurements which confirm the view that the 

 appearance is due to crushing. 



1 Dwelling in clay. 



