112 Frederick Chapman: Ostracoda. 



on the inner side and grooved on the outer. Valves equal. Surface- 

 smooth, with a muscle spot situated near the dorsal region of the- 

 anterior third, and a shallow depression (better seen in other un- 

 figured specimens), near the dorsal area and slightly anterior to the 

 middle. 



JJimens/oiis. — Length, 7.2 mm.; height, G mm.; thickness of 

 carapace, .3.2 nnn. 



Observations. — Only one other species of this genus has been. 

 hitherto recorded from Cambrian beds, viz., Isochilina Ottawa^ 

 Jones^ which occurs in the Calciferous Sandstone of Canada, but 

 which is also found in the Chazy Limestone (Arenig age). I. Ottawa 

 is only half the diameter of the present species, and is more oblong- 

 in shape. 



From its contour one might at first be inclined to refer this species' 

 to Aristozoe, Barrande, but that genus is more compressed and pod- 

 shaped, ^vith nodular prominences in the antero-dorsal region. 

 Moreover, it is less thickly calcified, as would be expected in a. 

 phyllocarid crustacean. 



Occurrence. — This large and conspicuous species seems fairly 

 common in the Curramulka Limestone. AH the specimens examined" 

 were from the Sw^eet collection, with the exception of a doubtful,, 

 partially buried carapace from the Tate collection, S. Australian- 

 Museum (lent by Mr. W. Howchin, F.G.S.). 



EXPLANATION OF PLATE IX. 



Fig. 1. — Leperditia tatei, sp. nov. ; a, right valve seen from the 

 side; h, profile. Holotype. Sweet coll. x 10. 



Fig. 2. — L.tatei, sp. nov.; a, left valve seen from the side; h, ven- 

 tral edge view. Paratype. Tate coll. x 10. 



Fig. 3. — L.tatei, sp. nov. ; a, left valve of a narrower specimen; h,. 

 profile. Paratype. Sweet coll. x 5. 



Fig. 4. — Leperditia capselki, sp. nov. ; a, left valve seen from the^ 

 side; h, profile. Holotype. Sweet coll. x 10. 



Fig. 5. — Isochilina sv:eeti, sp. nov., a, right valve seen from the 

 side; h, profile. Holotype. Sweet coll. x 5. 

 All the specimens are from the Upper Cambrian Limestone of 



Curramulka, South Australia. 



1 Ann. Majf. Nat. Hist., ser. 3, vol. i., 1858, p. 248, pi. x., fijrs. In-c. Geol. Surv. Can,„ 

 Orj?anic Remains, 1858, p. 97. pi. xi., flps. I4a-c. Ann. Majf. Nat. Hist., ser. 5, vol. xiv., 18&4.. 

 p. 846. 



