456 ARACHNIDA. 



BIBLIOGRAPHY. 

 Scorpionidcs. 



(434) El. Me tschnikoff. " Embryologie des Scorpions." Zdt.f.imss.Zool. 

 Bd. xxi. 1870. 



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



Psendoscorpionidce. 



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

 Zool., Bd. xxi. 1870. 



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

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

 3. Heft, and Annal. and Mag. Nat. History, 1876, XVIII. 197. 



Plialangidce. 



(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. 

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



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

 de VAnat. et de la Physiol. 1878. 



(442) E. Claparede. Recherches s. fei'ohttion des Araignccs. Utrecht, 1862. 



(443) Herold. De gencratione Araneornvi in Oz'o. Marburg, 1824. 



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

 Zeit. f. -Miss. Zool., Vol. xxvi. 1876. 



A carina. 



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

 xelles, t. xxiv. 



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

 XVIII. 1868. 



Formation of the layers and the embryonic envelopes in the 



TracJicata. 



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 

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



