Ix 



relationships of these groups has been discussed at considerable 

 length in ' Nature.' 



Professor Van Beneden has also read a memoir on the syste- 

 matic position of the Limuli and Trilobites, which last group he 

 considers must now be separated from the Crustacea, forming 

 with the scorpions, &c., a distinct branch of the Arachnida. 



Prof, Claus has published, in the sixteenth volume of the 

 ' Abhandlungen ' of the Eoyal Society of Gottingen, a highly im- 

 portant memoir on the Metamorphoses of the Squillida, one of 

 the most aberrant groups of the higher Crustacea, in which he 

 has apparently proved satisfactorily that the remarkable forms 

 called glass-crabs, described by Crustaceologists under the generic 

 names of Alima, Erichthus and Squillerichthus are only the early 

 states of species of Squillse. The memoir is accompanied by eight 

 elaborate plates crowded with figures, in which the development 

 of the Squillae through their different forms is carefully traced 

 and delineated. 



An elaborate memoir, by M. Balbiani, on the development of 

 the ovum of the species of the genus Phalangium, is published in 

 the ' Annales des Sciences Naturelles,' Serie V., vol. xvi. (pi. 1), 

 which presents two observations of much interest: 1st, the young 

 animal is in this state furnished with the full complement of four 

 pairs of legs ; and 2nd, these limbs, owing to their great length, 

 are in the egg-state folded back upon each other. Two plates 

 illustrate this memoir. 



A very excellent summary of Siebold's " New Researches in 

 Parthenogenesis" (' Beitrage zur Parthenogenesis der Arthro- 

 poden'), and indeed of the nature of that peculiar condition of 

 development, has been given by Mr. Ray Laukester in ' Nature,' 

 vol. vi. pp. 483 and 523. 



A memoir by Prof. Duncan, F.R.S., was read at the meeting of 

 the British Association, 1872, on Insect Metamorphosis regarded 

 as an acquired peculiarity by evolution. The minute anatomical 

 structure of the oesophagus, pylorus and stomach at different 

 stages of growth, and the gradual formation of the wings beneath 

 the skin of the larva upon the air-tubes and blind stigmata of the 

 second and third segments of the bod}'-, were carefully illustrated, 

 the author contending that " the wings are progressively deve- 

 loped, and that tbey grow from simple protoplasms into all their 

 beauty and complexity of form during the stages after the escape 



