ARACHNIDA. 



BIBLIOGRAPHY. 



Scorpionidtz. 



(434) El. Metschnikoff. " Embryologie des Scorpions." Zeit.f. iviss. Zool. 

 Bd. xxi. 1870. 



(435) H. Rathke. Reisebemerkungen aus Taurien (Scorpio), Leipzig, 1837. 



Pseudoscorpionidce. 



(436) El. Metschnikoff. "Entwicklungsgeschichte d. Chelifer." Zeit.f. wiss. 

 ZooL, Bd. xxi. 1870. 



(437) A. Stacker. " Entwicklung der Chthonius-Eier im Mutterleibe und die 

 Bildung des Blastoderms." Sitzung. konigl. bohmisch. Gesellschaft Wissensch., 1876, 

 3. Heft, and Anna!, and Mag. Nat. History, 1876, xviii. 197. 



Phalangida. 



(438) M. Balbiani. " Memoire sur le developpement des Phalangides." Ann. 

 Scien. Nat. Series v. Vol. xvi. 1872. 



A raneina. 



(439) M. Balbiani. "Memoire sur le developpement des Araneides." Ann. 

 Scien. Nat. Series v. Vol. xvn. 1873. 



(440) F. M. Balfour. "Notes on the development of the Araneina." Quart. 

 Journ. of Micr. Science, Vol. xx. 1880. 



(441) J. Barrois. "Recherches s. 1. developpement des Araign^es." Journal 

 de VAnat. et de la Physiol. 1878. 



(442) E. Claparede. Recherches s. Devolution des Araignees. Utrecht, 1862. 



(443) Her old. De gene ratione Araneorum in Ovo. Marburg, 1824. 



(444) H. Ludwig. " Ueber die Bildung des Blastoderms bei den Spinnen." 

 Zeit.f. wiss. Zool., Vol. xxvi. 1876. 



Acarina. 



(445) P. van Beneden. " Developpement de 1'Atax ypsilophora." Acad. Bru- 

 xelles, t. xxiv. 



(446) Ed. Claparede. " Studien viber Acarinen." Zeit.f. wiss. Zool., Bd. 

 xviii. 1868. 



Formation of the 'layers and the embryonic envelopes in the 



Tracheata. 



There is a striking constancy in the mode of formation of 

 the layers throughout the group. In the first place the hypo- 

 blast is not formed by a process which can be reduced to 

 invagination : in other words, there is no gastrula stage. 



