o I 8 Frederick Chapman : 



in a series of graceful curves, sometimes in a double, sigmoidal 

 or ear-shaped curve, or coiled closely in helicoid fashion. The- 

 branchlets are disposed along one face, the inner, except rarely 

 where recurved, and vary in length, being short and stout at the- 

 base, to long, flexible and slender nearer the distal end. The- 

 outer surfaces of the branchlets are pectinate to filamentous^ 

 generally recurved at the tip towards the axis, but occasionally 

 thrown forward. In the blue-grey shale of Keilor the impressions- 

 stand out clearly, being of much darker tint. The South Yarra 

 specimens, in yellow shale, are contrasted by bleaching, being 

 paler in tint, or as in the dark blue indurated sliale from the- 

 Domain lload Sewer, of a carbonaceous shade against the pale grey 

 matrix of the immediate surroundings. 



Dimensions. — Length of a large specimen, from the Melbourne- 

 district, about 4 cm. Length of another example, from South 

 Yarra, 17 mm.; length of branchlets, 3.5 mm. A specimen front 

 Keilor, 20 mm. long; length of longest branchlet, 12 mm.; depth, 

 1.25 mm.; depth of thickest brancldet, 3 mm. Thickness of axis, 

 about 1 mm. 



Eriihnce of eyes and dorsal appendices. — On one of the best 

 preserved specimens, which has been sharply flexed, can be made- 

 out, Avhen held at a low angle to reflected light, some depressions- 

 witli a central bulb, and an ofl'set of a fistulose shape just above, 

 and partially enclosing it. The axis of the branchial process in; 

 this specimen is transversely striated. 



Occurrence of prostomial gill-plumes of Trachyderma. 



Melhournian. In buff mudstone, Swanston Street Sewer, near- 

 Collins Street (F. P. Spry coll.), hard blue mudstone, Domain 

 Road Sewer, South Yarra (F. P. Spry coll.); blue mudstone. Haw- 

 thorn Road Main Drain (F. P. Spry coll.). 



Vrohahly Melhournian . Slaty-blue mudstone, four miles north- 

 west of Keilor (A. James coll.). Also tubes of Trachyderma with- 

 fragments of prostomial impressions (one pectinated), from Silu- 

 rian mudstone, probably on Warrandyte Anticline at Quarry near 

 Scotchman's Creek, Mulgrave (R. A. Keble coll.). 



General Ohser rations on the soft and other parts of Worms found' 

 Fossil. — In the Text-book of Zoology, Parker and Haswell,! refer- 

 ence is made to the occurrence of Chaetopods in the fossil condi- 

 tion, as follows : — 



I Vol. i., London, 1910, p. 448. 



