107 



The markings are very like P. Hedleyi, but the lateral area 

 makes a distinct species. 



Habitat. Port Esperance. One median valve. 



32. Plaxiphora pustulosa, sp. nov. 

 Plate xxv., fig, 7. 



One median valve was taken at Albany and is in perfect 

 condition. The valve is slightly arched and beaked. The 

 posterior part of the dorsal area has 12 bright-brown trans- 

 verse riblets divided by pale-green striae, rather crowded 

 toward the posterior. These riblets are continued into the 

 pleural area in rows of bright shiny pustules, longitudinally 

 parallel, and diminishing in number from seven near the dor- 

 sal area to one at the insertion plate. The lateral area is 

 slightly raised, but very distinct. It has three or four 

 radiating rays of the tear-drop pustules. 



Interior. The sinus is gracefully curved, colour rich 

 dark-brown, slightly pectinated. The sutural plates are 

 small. The rear part is folded over, making a white limy 

 sulcus, ending in one slit at the insertion plate. 



Habitat. Albany, Western Australia. One median 

 valve. 



Brighton, 



South Australia. 



EXPLANATION OF PLATES. 



Plate XXIV. 



la,b,c,d,e,f — Ischnochiton verconis, sp. nov. 

 :2a,b,c,d,e,f — Plaxiphora hedleyi sp. nov. 



Plate XXV. 



3a,b,c,d,e,f — Acanthochites subviridis, n. sp. 

 4a,b,c,d,e,f — Tonicia hullianus, sp. nov. 

 5a,b,c,d,e,f — Lepidopleurus niger, sp. nov. 

 6 — Plaxiphora zebra (median valve), sp. nov. 

 7 — Plaxiphora pustulosa (median valve), sp. nov. 



a, — Dorsal view of entire shell. 



b — Anterior valve. 



c — Median valve. 



d — Posterior valve. 



e — Lateral view of posterior valve. 



/ — Portion of girdle magnified. 



Sizes of type specimens are marked in each case 



