188 
Halysites orthopteroides, Etheridge fil. (Plates XXV., Figs. 22, 23 ; XXVI., Fig. 24). 
Halysites orthopteroides, Etheridge, jun., 1904, Mem. Geol. N. S. 
Wales, Pal. No. 13, pt. I., p. 25, pi. III., fig. 1 ; pi. VII., figs. 4, 5. 
Observations. —-The labyrinthine fenestrules and the characters of the 
tabulse are sufficient to define this species, as occurring in thin sections of the 
Mitta Mitta limestone. Fig. 24 of these plates is taken from a sheared 
example, much of the limestone of this district being deformed by dynanio- 
metamorphism. This is the first occurrence of H. orthopteroides in Victoria. 
It has been recorded from the Silurian of Co. Wellington, New South Wales. 
Occurrence. —In the grey limestone of the Mitta Mitta River, N.E. Gipps- 
land (Nos. 2698, 2699, ?2700). 
Halysites pycnoblastoides, Etheridge fil. (Plate XXVI., Fig. 25). 
Halysites pycnoblastoides, Etheridge, jun., 1904, Mem. Geol. Surv. N.S. 
Wales, Pal. No. 13, pi. I., p. 32, pi. IV., figs. 1, 2 ; pi. VIII., figs. 5, 6. 
Yabe, 1915, Rep. Tohoku University, Sendai, 2nd Ser., Geology, vol. IV., 
pt. 1., p. 36, pi. IX., figs. 3, 4. 
Observations. —-These Victorian examples, the first recorded, are well- 
defined in section. They show the oval, robust character of the autopores 
with their septal spines and the ill-defined mesopores. The differences between 
this form and the somewhat related H. sussmilchi are well shown in the 
present specimen. It is the rarest of the three species of the genus found here. 
In New South Wales it occurs at Spring Creek, Co. Ashburnham. Dr. Yabe 
recently described this form from Ta-Wan-Gai, near Y-chang, China. 
Occurrence. —-In the grey Silurian limestone of the Mitta Mitta River, 
N.E. Gippsland (No. 2700). 
Class POLYZOA. 
Fam. Fistuliporid^, Order Cyclostomata. 
Genus Fistulipora, McCoy. 
Fistulipora cowombatensis, sp. nov. (Plate XXVII., Figs. 26, 27). 
Description. —-Zoarium cylindrical or subrotund. Length of one example 
28 mm ; diameter, 13‘5 mm. In horizontal section the autopores or zooecia 
are circular and average P2 mm. longer diameter. The mesopores are 
smaller, angular to lobate, and average 1 mm. in diameter. Walls of the 
autopores and mesopores thin ; numerously perforated. In longitudinal 
section the mesopores are seen to be short and broad proportionally. 
Relationships. —The above species is distinct from the already described 
Fistulipora victoriw, Chapman,^ in having a coarser and more irregular 
structure, the autopores being often ill-defined and the mesopores sinuate 
or bilobed ; and further, the thin walls of the mesopores are numerously 
perforate. 
Two species of the genus from the Niagara Formation (Wenlockian) of 
North America somewhat resemble the present species, viz., F. lockportensis, 
Bassler,2 and F. tuberculosa, J. Hall sp.^ The former, however, has much 
larger autopores, whilst the latter exhibits a more open and irregular meso- 
poral structure in longitudinal section. 
Observations. —A point of great interest in connexion with this species 
is the constant occurrence of mural pores in the cyst-like walls of the meso¬ 
pores. In regard to this structure Dr. Nicholson has remarked on their 
^ See this publieatioTi, vol. III., pt. 3, 1914, p. 310, pi. LVIII., fig. 31 ; pi. LIX., figs. 32-34. 
“ U.S. Geol. Surv., Bull. No. 292, Ser. C. Geol. and Pal. 78, 1906, p. 23, pi. VII., figs. 1-3. 
^ Rhinopora tuberculosa, J. Hall. Nat. Hist. N. York, Pal. II., 1852, p. 170, pi. XLE., figs. 4a-c. 
Fistulipora tuberculosa, J. Hall sp., Ba,ssler, op. cit., 1906, p. 23, pi. VII., figs. 11-15 ; pi. VIII., figs. 7, 8 ; 
pi. XXIII., fig. 14. 
