90 EXTRACTS AND ABSTRACTS FROM FOREIGN JOURNALS. 



of growth of its shell, this genus constitutes a natural connecting link of 

 the Crustacea with the Acephalous Mollusca; in the rest of its struc- 

 ture, it is related to the Cirrhipeda, which come after the Crustacea. 

 3, The Isaura cycladoides does not acquire its bivalve shell or definitive 

 form until after a series of changes, during which it assumes succes- 

 sively the form of Artemia, Branchipus, and still more Apus in a young 

 state ; then, that of Daphnia, Lynda, Cypris, Limnadus, and Cyzicus 

 arrived at the adult state ; 4, Although this Branchiopod undergoes 

 very frequent changes, its shell, far from being caducous, as that of all 

 other Crustaceans with a bivalve shell, remains during the entire life of 

 the animal, and resembles also in this particular the coverings of the 

 Mollusca ; 5, It enlarges in the same manner as the nacreous portion 

 of the shell of the Malacozoaires, viz., by the addition of successive 

 larger, and more internal layers, the thickened margins of which form 

 at its external surface true striated marks of growth ; 6, These layers 

 may be readily separated from each other after a period of 24 hours' 

 maceration in caustic potass ; 7, The Isaura cycladoides is provided with 

 separate sexes. The male is at once distinguished from the female by 

 the presence of two pairs of appendages, situated in front of the abdo- 

 minal feet, and furnished at their free extremities with a kind of three- 

 fingered apparatus (griffes}, especially adapted to retain the female 

 during copulation ; 8, This animal habitually swims on the abdomen, 

 that is to say, the reverse of other Branchiopodous Crustaceans, and 

 particularly Apus and Limnadus, to both of which it is nearly allied ; 

 9, Its eggs, similar to those of Apus, Limnadus, and Branchipus, appear 

 to possess the power of supporting desiccation for a long period, with- 

 out in the meantime losing the power of germination. 6th Dec. 1841, 

 p. 1068. 



Brogniart presented to the Academy, in the name of the author, 

 M. H. R. Gdppert, a Memoir on the Anatomical Structure of Conifers. 

 6th Dec. 1841, p. 1071. 



Great Prize in Physical Sciences Proposed in the year 1837 for 

 1839, and submitted again for 1843. The Academy proposed as the 

 subject of the Great Prize in Physical Sciences, at the Public Sitting in 

 1839, the following question : 



" Determine, by precise experiment, what is the succession of che- 

 mical, physical, and organic changes which take place in the egg during 

 the development of the foetus in Birds and Batrachians. 



" The candidates are required to render an account of the relations of 

 the egg with the natural milieu ambiant ; and to examine, by direct ex- 

 periment, the influence of artificial changes on the temperature and che- 

 mical composition of this milieu." 



" Within the last few years, several observers have directed attention 

 to, and produced some profound researches on the development of the 

 chick in the egg ; and have extended their inquiries to the develop- 

 ment of the foetus in other oviparous animals. Generally speaking, 

 their examinations have principally been conducted in an anatomical 



