Victorian Fossils, Fart XXII. 317 



have bet?ii described as T. crassiiuha, Chapman ^^ and T. cf. 

 squatnosa, Phillips.'^ 1'he soft appendages now referred to appar- 

 ently belong to the former species, though this can only Ije surmised 

 in the majority of cases from the tubes associated with them. 



Trachydekma, sp. cf. CKASSITUBA, Cliapni., et alii specLeriun. 



General OO.servations. — In 1910 the writer described two specific 

 forms of worm-tubes from both the Melbournian and Yeringian 

 beds of Victoria. These were referred to the genus Trnchyderma 

 of Phillips, similar fossils having been recorded from the English 

 Ludlow series and the Silurian of Burma. 



These tubes are normally found in the condition of nmd-casts, 

 with a harder outer covering, probably originally chitinous or sub- 



"C'hitiiious, of the nature of an organic slime and mud fabric. 



No remains of any soft parts of the worms of tliis generic type 



.seem to have been previously recognised. Many examples, now 

 referred to the cephalic (prostomial) appendages of these tube- 

 building worms, have from time to time been found in the 



-Silurian mudstone of South Yarra and Melbourne by Mr. F. P. 



,i5pry, but until lately these specimens baffled all attempts to estab- 

 lish their true nature. Within the last few months Mr. A. James, 

 B.A., B.Sc, was so fortunate as to find, in a l)ed of this fine- 

 textured blue nmdstone, about four miles north-west of Keilor, 

 some beautifully preserved examples of fossil remains similar to 

 those previously referred to as occurring near Melbourne. 



That tliese fossils have a direct relationsliip to TrachyderitKi is 



^strongly supported by the fact that they are found associated with 

 Trachyderma tubes at South Yarra and Xeilor,^ in whicli deposits 

 they are the only fossils to be found. Moreover, the morphological 



; structure of the impressions and caibonaceous stains, here referred 

 to these gill-like cirri, and which are often surprisingly clear and 

 sharp, resemble no other animal organism, not excepting pennatu- 

 lids, cirripedes and other like structures. As i-egards a plant 



• origin for these lemains, the single or double series of serrae witli 

 a lioUow flexuous canal, preclude them fi-om any sucli leference. 



DeHcription of prostomial (/ill-phimea. — The axis of the plumes 

 is a hollow tul)e, well seen in inore than one exam]>1e. It is l>ent 



1 I'roc. Roy. Sex: Nictoiia, vol. xxii. (\.8 ), pt. ii., IIHO, p. 10^, pi. xwii, tijj.s. 1«, 6, 2, .{, .1 : 

 pi. xxix., fi;;. 1. 



2 n»id., p. 104, pi. xwii., fijf. f). 



3 At Keilor t.he tiil)ex .vet disco\ t-red are rel.-ited to T. crasfit aba in liaviii); a thick wall, Vnit it 

 is of a more .sk-nder form, and inav, on findirij,' fwrthet examples, prove to be new. The tjill-plumes 

 from the two localities also show uliyht differences. 



2a 



