EXPLANATION OF PLATES. 
Fig. Prats I. 
1, 2.—Interior and exterior of valve of Pronucula mesembrina Hedley. Type specimen. 
3, 4.—Dorsal and lateral view of Malletia sabrina Hedley. Type specimen. 
5, 6, 7.—Exterior, bare and dressed in epidermis, and hinge of Philippiella bagei Hedley. Type 
specimen. 
8, 9, 10, 11.—Exterior, bare and dressed in epidermis, hinge and prodissoconch of Philippiella hamiltont 
Hedley. Type specimen. 
12, 13.—Exterior, draped in epidermis, and hinge of Philippiella orbiculata Hedley. Type specimen. 
Prats I. 
14, 15.—Broken valve of adult type of Chlamys subantarctica Hedley, and a young shell, 6mm. high, 
assigned to this species. 
16.—Exterior of Lima closet Hedley. Type specimen. 
17, 18, 19.— Exterior and hinges of Gaimardia smithi Suter. 
20, 21, 22.—Exterior and hinges of Gaimardia trapezina Lamk., var. coccinea Hedley. 
23, 24.—Exterior and hinge of Kidderia macquariensis Hedley. Type specimen. 
25, 26, 27 Exterior and hinges of Kidderia pusilla Gould. 
Puate III. 
28.—Exterior of Pholadomya antarctica Hedley. Type specimen. 
29, 30.—Dorsal and lateral views of Pholadomya mawsont Hedley. Type specimen. 
31, 32.—Dorsal and lateral views of Pholadomya adelaidis Hedley. Type specimen. 
33, 34.—Dorsal and lateral aspects of Venericardia astartoides von Martens. 
35, 36, 37.—Anterior and lateral aspects and hinge of Ptychocardia rudis Hedley. Type specimen. _ 
38, 39.—Exterior and hinge of Pseudokellia stillwelli Hedley. Type specimen. 
Prats IV, 
40, 41 —Exterior and hinge of Rochefortia macquariensis Hedley. Type specimen. 
42, 43, 44.—Exterior and hinge of Laswa consanguinea Smith. 
45, 46.—Hinge of Lasea australis Lamarck, from Gerrigong, New South Wales, for comparison 
with L. consanguinea. 
47,48, 49, 50.—Dorsal, lateral, and interior aspects of type specimen of Ohione mawsont Hedley. Lateral 
aspect of radially striated variety. 
51, 52, 53.—Exterior and hinges of Saxicava antarctica Philippi. 
Puate V. 
54, 55.—Dorsal and oral aspects of Schsmope subantarctica Hedley. Type specimen. 
56, 57—Basal and peripheral aspects of Margarella macquariensis Hedley. Type specimen. 
58.—__Submargarita smithiana Hedley. Type specimen. 
59.—Minolia thielei Hedley. Type specimen, 
60, 61.—Shell and animal (from alcoholic specimen) of Photinula coruscans Hedley. Type specimen. 
