316 



Frederick Chapman : 



The structure of the covering is, in the arrangement of the 

 incremental lines and rings, more analogous to that of the 

 Serpulidae than to what occurs/ on other groups of Annelida, or 

 on the fistuliform Kadiaria and Ascidiae. It may, in fact, be 

 pretty exactly paralleled on large specimens of Serpulidae.'' 



From figures and descriptions of the various species of the 

 genus — as T. coriacea, Phillips, ^ T. l^itris, McCoy, 2 T. iierrata, 

 Salter, 3 and T. squam&m, Phillips, 4 of Llandeilo to Upper Ludlow 

 (Lower Ordovician to Upper Silurian) age — it is seen that a thick 

 coriaceous tube with a more or less obtusely rounded extremity 

 serve to separate it from Salter's genus Scolecoderma,^ a species of 

 which, S. antiquissima,^ was formerly referred by Salter to 

 Trachyderma, but which has a thin membranous tube and a taper- 

 ing and pointed extremity. 



With reference to tlie scope of Scoltcoderma as a genus, we may 

 note that there is room for it in its lestricted sense, but from 

 Mr. K. Etheridge senior's interpretation it would embrace tlie 

 earlier described genus Trachf/derma, Thus, in Salter's Palae- 

 ontology,^ revised by R. Etheridge in 18<S1, we read : — 



** Scolecoderma, Salter, 1866. Mr. Salter proposed tliis term 

 for all such menibranous tubes (often much compressed) of anne- 

 lides, found in palaeozoic rocks, as are not clearly referable to 

 the more calcareous, or at least semi-calcareous tubes of SerpiiJites. 

 They are very common. In a few cases it is possible we may mistake 

 impressions of sea-weed for these; but their position in the beds, 

 often vertical or oblique to them, will determine that they do not 

 belong to the algae; and the want of any branches or subdivision 

 of the frond will also tend to determine them. Sometimes they are 

 cylindrical, n\ore often compressed, and we may distinguish this 

 convenient but artificial genus, comprising probably many different 

 genera of annelida from the conmion Scoliten by its having clearly 

 possessed a wall or tube which renders the cast easily separable 

 from the matrix, whilst Scolites only represents the track of the 

 burrow." 



The two species of Trnchyderwa previously met with in Victoria 



1 Mem. Soc. Geol. Smv. Gt. Brit., vol ii., pt. i., 1848, p. 3.S1, pi. iv., fi<,'8. 1, 2. 



2 Brit. I'al. Fossils. 1852, p. J33, pi. id., fi-,^ 13. 



3 Quart. Jonrii. Geol. Soc, vol. \\ , 1864, p. 200, pi. xv., fiyr. 9. 



4 Mem Geol. Siirv. Gt. Brit., vol. ii., pt. i., 1848. p. 332, pi. iv., fi<f. 3. AlbO 7'. of. squamosa^ 

 Reed, Pal. Indica. (N Ser.). vol. ii., No. 3, 190«, p. 129, pi. vii,. fij:. 17. 



5 Mem. Siirv. Geol. Gt. Brit., vol. iii., 1866, p. 292 ; 2iid ed., 1881, )>. 484. 



6 Salter, Cat Camhro-Silnriaii Fos.siIs, 1873, p. \0. 



7 Mem Geol. Surv. Gt. Brit., vol. iii. 1881, 2i)d ed., p. 484. 



