SILURIAN BIVALVED MOLLUSCA OF VICTORIA. 
very closely in this respect. The Victorian specimen may also 
be compared with P. fecunda, J. Hall,* although that species 
has a marked depression in front of the umbonal ridge. 
P. tenuistriata oceurs in the Hamilton Group in the States 
of New York and Pennsylvania. 
Horizon and Locality—Silurian (Melbournian). In the 
whitish mudstone of Merri Creek, Sects. 2 and 3, Kalkallo, coll. 
Geol. Surv. Vict. Bb 3. [967.] 
Family Parallelodontide. 
Genus PARALLELODON, Meek and Worthen, 1866. 
Parallelodon spryi, sp. nov. Plate I., Fig. 3. 
Description.—Shell of medium size, subovate; cardinal line 
nearly straight, meeting the posterior border almost at right 
angles, but slightly upturned; ventral border convex, narrower 
anteriorly, and broadly curved posteriorly. Median area 
swollen, rising prominently towards the beaks, which are 
situated sub-anteriorly; posterior region compressed. Cardinal 
area exposed in the type specimen, showing what appears to be 
the extremity of a series of about six parallel and_ slightly 
oblique hinge-teeth. Surface of valves grooved concentrically, 
the highest part of the ridges being obliquely striated, the 
striz radiating from the beaks. Indications present of a large 
anterior muscle impression situated close to the cardinal area. 
Measurements.—Length, about 26 mm.; height, 17 mm.; 
thickness of entire shell, 8 mm. 
Observations.—The presence of a parallel series of anterior 
teeth points to relationship with Parallelodon, sensu stricto. 
The genus Macrodon, Lycett, 1845 (nom. emend. Macrodus, 
Beushausen, 1895) is closely allied, and is regarded by Dallt 
as synonymous. The latter genus differs in some slight respects, 
such as the obliquity of the anterior teeth. Should both types 
prove to be congeneric, the former name will stand, since the 
latter had been used by J. Miiller for a genus of fishes, whilst 
Beushausen’s name is of much more recent date. 
*Tom. supra cit., p. 336, Pl. XLIX., Figs. 13, 15-24. 
+ Abhand]. von Preuss. Geol. Landesanst., N. F. Heft. XVII. p. 36. 
+ Text-book of Palwontology, Zittel-Eastman, 1900, p. 364. 
[ 38 ] 
