522 Geological Society. 



teen days, by means of the funis, which is continuous with a second, 

 or external membrane, the chorion, which lines the interior of the 

 shell. He states that the liberation of the embryo from the shell is 

 not effected by any effort of its own, but by the expansive force of 

 the growth of its body. He describes, also, another important fact 

 which had been overlooked by previous observers, relating to the mode 

 and place of origin of the new segment of the body in the Julida?. 

 The new segments are always produced in a germinal membrane im- 

 mediately before the penultimate segment, which segment, with the 

 anal one, remains permanent throughout the life of the animal. The 

 production of the first set of new segments is commenced even be- 

 fore the animal has burst from the amnion. After leaving the am- 

 nion, the young Julus possesses six pair of legs, as stated by Savi 

 and Waga ; but the author remarks, in addition, that, notwithstand- 

 ing this, it is still inclosed in another tunic, the proper skin of the 

 embryo, beneath which new segments are being formed, and which 

 begins to be detached before the embryo has left the amnion. He 

 suggests whether this may not be the representative of the proper 

 tunic of the germinal vesicle. After minutely describing the em- 

 bryo, and showing that its body is still formed of cells, he states 

 that four pairs of new legs are forming beneath this tunic, and that, 

 on the twenty-sixth day, the young animal throws off this cover- 

 ing, and the legs are developed, and also the six new segments, to a 

 further extent. The animal then takes food, the segments become 

 developed to the same extent as the original ones, until the forty- 

 seventh day, when it again changes its skin, new segments are again 

 produced, and new legs to those segments last formed. In this way 

 it passes through several changes, developing first segments and then 

 legs. 



One remarkable circumstance stated is, that the production of 

 segments is sextuple in the Julidse ; but this does not hold in other 

 genera, in some of which it is quadruple, and in others double ; but 

 these peculiarities appear in all cases to be characteristic of each 

 distinct genus. In conclusion, he confirms the observation already 

 made by M. Gervais, that the number of eyes is increased as the 

 animal advances in its transformations. The author concludes by 

 stating that he proposes continuing these observations on the My- 

 riapoda at some future period. 



The paper is accompanied by drawings of the parts described, 

 and of the successive changes which take place during the deve- 

 lopment of the animal. 



GEOLOGICAL SOCIETY. 

 [Continued from p. 500.] 



April 7, 1841. — A paper was first read, entitled " A Notice on 

 the Occurrence of Triassic Fishes in British Strata," by Sir Philip 

 Grey Egerton, Bart., M.P., F.G.S. 



Were the muschelkalk abstracted from the continental series of 

 beds called the Trias, and the keuper made to rest on the bunter 



