Victorian Fossils. 6 



Order PRIONODESMACEA (Isodonta). 

 P^am. PECTINIDAE. 



Genus Hinnites, Defrance. 

 HiNNiTES MULDEBi, sp. nov. (Plate II., Figs. 9, 10.) 



Description. — Valves very inaequilateral, oblique, depressed. An- 

 terior margin gently rounded near the umbo, truncately rounded to- 

 wards the ventral, the posterior region is well-rounded, the margin 

 sweeping forward and upward in an almost straight line to the um- 

 bonal angle made with the anterior. The neanic part of the shell is 

 pectinoid, and feebly radiately striate, there being about sixteen fine 

 costae. The ephebic and possibly gerontic stages show the charac- 

 teristic irregularly undulose surface caused by the alternately con- 

 cave and convex condition of the ventral edge; shell surface of later 

 stages with a similarly striate and radiate ornament. Muscle im- 

 pression large. Resilium small, acutely triangular. 



Dimensions. — Left valve, length, 57 mm.; height, 59 mm. Height 

 of pectinoid stage, 16.5 mm. 



Observations. — The following characters distinguish this species 

 from the allied Hinnites corioensis, McCoy": — 



1. Shell narrower or higher and more oblique. 



2. Radial striae of pectinoid stage more numerous and finer. 



3. Radial striae on ostreiform area not so strongly frilled 



by the crossing of the growth lines, the surface being 

 sinuously striate, and not verriculate. 

 Occurrence. — In the white polyzoal limestone of Batesford, near 

 Geelong. Janjukian (Miocene). 



Two valves presented by the late J. F. Mulder, Esq. The species 

 is named after its discoverer in recognition of his assiduous and 

 successful work in bringing to light many interesting Cainozoic forms. 



Fam. SPONDYLIDAE. 



Genus Plicatula, Lamarck. 

 Plicatula youngi, sp. nov. (Plate I., Figs. 4, 5.) 



Description. — Shell moderately thin, subtrigonal, high, oblique; 

 left valve strongly arched. With about 20 low, rounded plaits, only 

 conspicuous towards the ventral margin, and apparently once divided 

 from their base near the medium area. Umbonal area rugose with 

 irregular folds. Growth-lines more strongly marked towards the ven- 

 tral border and imbricated. The pair of strong teeth in the right 

 valve are fused to a fairly large triangular area, which is transversely 

 striate. 



Dimensions. — Height of shell (right valve), 26 mm.; length, 17 

 mm.; depth of valve, 7 mm. 



7. Prodomus Palaeont., Dec, vi., 1879, p. 31, pi. Iviii. 



