Geological Society, 391 



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 

 embrj'o, beneath which new segments are being formed, and which 

 begins to be detached before the embrj^o 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 ]\Iy- 

 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. 



AjirU 7, 1841. — A paper was 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 hunter 

 sandstone. Sir Philip Egerton says, it would be difficult, if not im- 

 possible, to define the proper limits of these formations. The new 

 red sandstone of England, the equivalent of the trias, presents this 

 difficulty, every endeavour to find the muschelkalk having failed ; 

 and therefore geologists are compelled either to consider the keuper, 

 the upper member of the trias, to be also wanting, or to be merged 

 in the mass of alternating marls and sandstones comprising the new 

 red series. Lithological structure, consequently, being of no value, 

 palscontological evidence, the author says, becomes of great import- 

 ance. The beautiful results arrived at by Mr. Owen respecting the 

 Batrachian remains found near Warwick, tend, Sir Philip Egerton 

 states, to render the existence of the keuper extremely probable. 



