XXXIX 



appeared, there remained, of the vertebrata, only the three orders 

 of reptiles whose embryological history was stilled untouched. To 

 these, therefore, Rathke resolved to extend his inquiries, and in 

 1838 produced his account of the embryogeny of the snake (Coluber 

 natrix), and ten years later that of the Testudines. Both works are 

 replete with new matter, and in that on the serpent especially the 

 development of the several organs from commencement to maturity 

 is handled with a depth and thoroughness of treatment hitherto un- 

 surpassed. The third monography on the development of Crocodiles 

 has been left by him nearly complete, and, we learn, will be published 

 as a posthumous work. 



The foundation of our more accurate knowledge of the embryology 

 of the Articulata may be said to have been laid by Rathke' s well- 

 known memoir on the development of the river- crab, which appeared 

 in 1829, and for which he obtained the Gold Medal of the French 

 Academy of Sciences. He afterwards availed himself of the oppor- 

 tunities afforded him by his residence at Dorpat to extend his re- 

 searches on the Crustacea ; and with the view of prosecuting his 

 inquiries on marine Invertebrata, he made a voyage from Dorpat 

 to the Crimea in 1833, and another from Konigsberg to the shores of 

 Norway in 1839. 



In the latter years of his life Rathke was engaged in two works 

 which he has left nearly in a complete state one on the develop- 

 ment of the snail, the other on Nephelis and some allied aimelides. 

 He had long intended to publish a systematic treatise on Embryo- 

 logy and Comparative Anatomy founded on his academical lectures ; 

 this intention he did not live to carry out, but since his death the 

 outlines of his lectures on the development of the vertebrata have 

 been published under the title of " Entwickelungsgeschichte der 

 Wirbelthiere," 8vo. Leipsic, 1861. 



Indefatigably employed as an original inquirer, Rathke was none 

 the less attentive to his duties as an Academical Professor. Up to 

 the year of his death he was favoured with excellent health, but after 

 suffering some time from severe catarrh, from which he partially 

 recovered, he was cut off suddenly by an apoplectic seizure on the 

 15th of September, 1860. 



Most of the eminent Societies of Europe enrolled Rathke among 



