Tertianj.-] PALEONTOLOGY OF VICTORIA. [Mollusca. 



I find tins species varies considerably in the length of the 

 anterior canal — in one extreme sjiecimen almost a monstrosity, 

 its proportion to the length is only -^g- ; but between this and the 

 normal type are so many intervening sjiecimens as to indicate a 

 variety brevis, not having any geological significance, however, as 

 these irregulaz'ly shortened specimens occur with the others. 



Common in the Oligocene Tertiary clays between Mount Martha 

 and Mount Eliza in Hobson's Bay ; less common in similar clays 

 at Fyansford. 



Common in similar clays (A'' 9) 3 miles west of mouth of 

 Gellibrand River. 



Explanation or Figures. 



Plates XXVIII. and XXIX. — Fig. 2, normal specimen, dorsal view, natural size. Fig. 2a, 

 same specimen, ventral view. Fig. 2b, same specimen, profile view. 



Plates XXVIII. and XXIX., Figs. 3-3c. 

 • CYPR^A (TRIVIA) AVELLANOIDES (McCoy). 



Description. — Very thin ovato-g'lobose, transverse section nearlj' three-fourths 

 of a circle from the otiter lip, the remainder of the inner lip curving' more rapidly, 

 olitnsely rounded behind, slighth' tapering- in front to the short scarcelj'-notched 

 cnnal; aperture narrow, of nearly equal width throughout {about 7 times longer 

 than wide), the outer and inner lips nearly parallel, terminating' in a very short 

 stiaight channel in front, but abruptly curved to the right with the thicker outer lip 

 behind; spire not prominent, of 3h turns. Surface crossed by very narrow sharply 

 defined verj' prominent thread-like ridges, varying from 35 at 1 inch long to 23 at 

 4 lines long, on the right .*ide, rarely dichotomising irregularlj', or stopping short, more 

 often turning abruptly out of their course with a branch-like bend to one side, so as 

 to intercalate short ridges between a longer pair, separated by sharply-defined broad 

 i^at spaces, usually three or four times wider than the ridges, faintly indented 

 with broad transverse scarcely visible marks. The ridges are usually interrupted 

 by a narrow shallow longitudinal depressed smooth space along the middle of the 

 back; 5, 6, or 7 pass vertically over the spiral whorls, and on tlie inner lip they are 

 iiitiected angularly at the edge of the aperture to form a concave inner lip as wide 

 as the mouth, and terminate in tubercles on its inner edge; the dorsal end not 

 swollen, sometime.s, though rarely, joining from each side, effacing the dorsal sulcus, 

 which when present varies irregularly from half a line to a line in width in a 

 specimen of the ordinary size of 10 lines. Greate.'^t length of very large specimen 

 from anterior canal to most posterior part of outer lip, 1 inch 2 lines ; in jn'oportion 

 thereto, to end of sjiire, i'(f ^ ; width, yVrrj height, I'jfj ; width of mouth, -i^^; a 



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