1895.] Presents. 385 



the deviations from the average occurred with a frequency indicated 

 by the theoretical law of error. The measurements of the aboral 

 arm-length did not agree so well, possibly owing to dimorphism. 

 The relative probable error of the smaller larvae was greater than 

 that of the larger ones, in the proportion of 63 to 57. As most of 

 the smaller larvae were obtained in the summer months, with pre- 

 sumably not quite mature ova, it is probable that the variability in 

 the size, as well as the actual size of the larvae, is affected by the 

 time of the year in which the fertilisations are made. The varia- 

 bility is also affected by the temperature of development, it reaching 

 a maximum at 18 to 20. The variability of the organs of echino- 

 derm larvae is much greater than in the case of higher animals. 

 Thus the probable error of the body-length is 6'1 per cent., of the 

 aboral arm -length 11 '3 per cent., and of the oral arm-leDgth 9 '4 per 

 cent. 



Presents, February 28, 1895. 



Transactions. 



Acireale : Accademia di Scienze, Lettere e Arti dei Zelanti. Atti 

 e Rendiconti. Vol. V. 8vo. Acireale 1894. 



The Academy. 



Buda-Pesth : Ungarische Geologische Gesellschaft. Foldtani 

 Kozlony. Kotet XXIV. Fiizet 1112. 8vo. Budapest 1894 ; 

 Jahresbericht. 1892. 8vo. Budapest 1894. The Society. 

 Cracow: Academic des Sciences. Bulletin International. Janvier, 

 1895. 8vo. Cracovie. The Academy. 



Frankfort-on-the-Main : Senckenbergische Naturforschende Ge- 

 sellschaft. Abhandlungen. Bd. XVIII. Heft 4. 8vo. Frank- 

 furt a. M. 1895. The Society. 

 Leipsic : Astronomische Gesellschaft. Vierteljahrsschrift. Jahrg. 

 XXIX. Heft 4. 8vo. Leipzig 1894. The Society. 

 Konigl. Sachsische Gesellschaft der Wissenschaften. Abhand- 

 lungen (Math.-phys. Classe). Bd. XXI. No. 3. 8vo. 

 Leipzig 1894. The Society 



Observations and Reports. 



Berlin : Konigliche Sternwarte. Astronomisches Jahrbuch. 1897. 



8vo. Berlin 1895. The Observatory. 



Madras : Government Observatory. Results of Observations of 



the Fixed Stars made with the Meridian Circle in the Years 



1883-87. 4to. Madras 1894. The Observatory. 



Milan : R. Osservatorio Astronomico di Brera. Osservazioni 



Meteorologiche. 1894. 4to. Milano. The Observatory. 



VOL. LVII. 2 F 



