216 PKOCEEDINGS OF THE M^VIACOLOGICAL SOCIETY. 



laud-shell fauna, but little known prior to the expedition, has been 

 most considerably extended, and in its characters it is found to 

 approximate that of Sub-Tropical West Australia. 



The study of the Australian Mollusca, as you are aware, has played 

 an important part in the recent revival of controversies concerning 

 the history of the Australian continent, and notably in the delimitation 

 of Tate's Larapintine or Central Ereraian Region. 



Mr. Hedley has contribnted to the Keport upon the Mollusca of the 

 Horn Expedition, an appendix dealing with the anatomy of some few 

 forms which were sufficiently well preserved for dissection, and has 

 arrived at the instructive conclusion that in relying wholly upon 

 salient superficial characters of shells and 'teeth,' we appear to be 

 associating together species markedly distinct in the structure of their 

 viscera. Mr. Hedley approaches the study of tlie Mollusca from the 

 broader standpoint of Pilsbry, who has done so much for recent 

 advancement of Malacology; and, since his work has thus a special 

 value, 1 the more readily draw your attention to his ingenious theory ' 

 of instability of the 'Antarctica,' for in a combination of this with 

 the theory of a South Pacific Mesozoic Continent, as originally con- 

 ceived by Huxley, the nearest approach to the truth concerning that 

 now vexed question appears to me to lie. 



Progress in the study of minute anatomy and development during 

 the year has borne good fruit ; and foremost for recognition there 

 stands the third part of F. Bernard's monograph'^ upon the hinge of 

 the bivalved molluscs, to which. I have already alluded, and upon 

 which our Editor gave us, in the autumn, an instructive demon- 

 stration. Bernard's announcement that the ligament is invariably 

 internal in origin, that the various types of cardinal teeth are due 

 to irregularity in growth of a series of ridges, and that the ligament 

 of the adult Mytilus is a secondarily formed structure which overrides 

 the 'teeth,' is full of interest and importance. Dfeissensia, in his 

 hands, is removed from the Mytilida^ ; and his discovery that, in 

 respect to the retention of larval (' prodissoconch ') crenulations and 

 the non-development of true 'teeth,' the adult Ostrcea and the 

 Pectens are, as it were, persistently embryonic, is most luminous, 

 seeing it comes at a time when the study of several of the great 

 groups of animals is showing us that, as concerns individual organs, 

 the lowest term is not unfrequently retained by the most generally 

 specialized forms. 



Since the publication of this most important monograph, Bernard 

 has briefly announced the discovery,^ among some mollusca collected 

 by M. Eilhol and others in the Islands of Stewart and St. Paul, 

 of two new Pelecypoda, Hochdetteria and Condylocardia. For the 

 latter he is compelled to create a new family ; and the former excites 



1 C. Hedley, Ann. and Mag. Nat. Hist., ser. VI, vol. xvii, p. 111. 

 "^ F. Bernard, Bull. Soc. Geol. France, ser. Ill, torn, xxiv, p. 412. 

 3 F. Bernard, Bull. Mus. Hist. Nat. Paris, 1896, p. 193. 



