199 
Affinities. — T. acclinans diifers from T. approximatus in several 
respects; of these, the important differences are; — 
(a) The gradual widening of the stipes of the first-named com¬ 
pared to rajiid widening of the second. 
(b) The gentle intral curvature cf the main stipes of the first- 
named compared to the rapid, strong curvature of the 
second. 
(c) The absence of that parallelism in the first-named is charac¬ 
teristic in the second, which, although not constant and 
depending on the mode of preservation, is evidence of 
essential differences in the two forms. 
Young species of T. acclinans bear certain resemblances to T. quad- 
rihrachiatius. The conditions of growdh of both species are not unlike, 
but they will readily be separated by the thecal differences and the 
disposition of the main stipes. 
A s so dates —• 
T. acclinans is found with T. approximatus. 
T. decipiens, 'Clonograptus riguhis var. tenelhis, T. fruticosus, Ac. 
Its associates are practically those of T. approximatus. 
Horizon and Localities — 
Lower Ordovician, Upper Cambrian. 
It is thought that T. acclinans will be found to be a slightly 
younger form than T. approximatus, and will, therefore, have some 
value as a subzonal formb 
The localities at which this species has been found are Hustler’s 
Hill, One Tree Hill syncline (Yalentine-.street), Bendigo, Boolara, 
Yewstead, &c. 
DECLINED SERIES. 
Tetragraptus DECTP3ENS, T. S. Hall (Plate XXXIV., Pig. 1a-e). 
The late Dr. Hall, as far back as 1898, describecP Tetragraptus 
decipiens, and figured in outline its polypary. The writer had lately 
found the horizon where this species attains the maximum of its de¬ 
velopment—in other words, the typical T. decipieyis subzone (L3) of 
the Lancefield zone. It O'ccurs * *abcut 800 feet below the base of the 
Bendigo zone (actual thickness of beds), and is typically developed on 
the Flag anticline where it is crossed by Valentine-street, Bendigo, im¬ 
mediately opposite the Central Bendigo Mine. 
In view of the importance of this species in subzoning the upper 
part of the Lanceifield, and possibly the lower part of the Bendigo zones, 
it has been considered advisable to amplify the description with addi¬ 
tional information to hand and re-figure it. 
7492.-7 
^ Vide p. 197. ante. 
* r. S. Hall, Proo. Roy.Soc. Viet. XI., 1809, p. 108, 
