Tertiary.'] PALAEONTOLOGY OF VICTORIA. [Echinodermata. 



anal opening (but faint indistinct traces apparently visible on the abraded surface of 

 the figured specimen of a V-shaped continuation from one side to the other 

 descending under the anal opening). Tuberculation nearly uniform (averaging 14 

 in a space of six lines) over the whole of the upper surface, except on each side of 

 the anterior sulcus, which has a few rows of larger and more widely separated ones 

 (averaging about 5 to 8 in six lines) ; slightly smaller and more crowded within the 

 fasciole near the vertex ; each mammillated and perforated crenulated tubercle is 

 surrounded by a few miliary rows of granules. Length, 7 inches 6 lines ; in 

 proportion thereto, greatest width, a little behind middle, ^^ ; apex to front margin, 

 j^ ; depth, ^g$ ; length of anterior lateral ambulacra, ^ 7 ; greatest width of 

 ditto, -^ ; length of posterior lateral ambulacra, -fo ; width of ditto, 

 depth of notch in front margin, 3 



This gigantic species is rarely preserved entire, and I am as yet 

 uncertain whether the lateral marginal fasciole is continuous under 

 the anal aperture, owing to the imperfect preservation of the 

 surface in the specimens at my disposal ; I think I see traces of it 

 in the normal position proper to the genus ; it is perfectly clear on 

 both sides from the middle to the posterior end as figured, and it is 

 also perfectly clear that it does not join the peripetalous fasciole; so 

 I refer the fossil provisionally to Pericosmus as an aberrant species, 

 although the marginal fasciole seems obsolete in the anterior half. 



The species of Pericosmus are chiefly known in the Miocene 

 Tertiary beds of Malta, and none are known of more recent age, 

 thus bearing out my original reference to the Miocene period of 

 the strata of the Victorian localities in which the following species 

 occur. 



Rare in the Miocene Tertiary beds on bank of Murray, near 

 Junction with the Darling (the figured specimen presented by 

 J. Wigley, Esq.), and in similar strata of Corio Bay. 



EXPLANATION OF FIGURES. 



Plate LXIV. Fig. 1, upper surface, natural size, showing form of peripetalous fasciole, 

 the ambulacra and the lateral fasciole from its apparent origin on each side behind the middle. 

 Fig. la, one of the crenulated tubercles, viewed from above, magnified. Fig. 16, same, viewed 

 from side. Fig. Ic, portion of fasciole, magnified. Fig. Id, lateral ambulacral plate and pair 

 of pores, magnified. Fig. le, plate of anterior ambulacrum and small pair of pores, magnified. 



Plate LXV. Fig. 1, same specimen, viewed in profile, natural size, showing peripetalous 

 fasciole and the posterior lateral fasciole. Fig. la, same specimen, viewed from posterior end, 

 showing the narrow posterior depression with the downward bend of the lateral fasciole on each 

 aide near it. 



FREDERICK McCoY. 



[16] 



