THI<1 DKVELOPMENT OF ABMETUS PUMILIO. 597 



LlTERATUEE, 



The object of this paper is to supply, as far as the materials 

 at my disposal permit, a gap in the literature of the embryology 

 of the Arachnids. Only three papers have as yet appeared 

 treating the development of the Pedipalps. Of these one 

 is on the development of the Thelyphonida3, the other two 

 treating the development of the Phi-ynidae. Their titles 

 are — (1) Dr. Strubell (42), 'Zur Entwicklungsgeschichte 

 der Pedipalpen ' (Vorliinfige Mittheilung) ; (2) Sophie 

 Pereyaslawzevva (37 and 38) : (o) ' Les premiers stades du 

 developpement des Pedipalpes ; ' [h) 'Les derniers stades dn 

 developpement des Pedipalpes;' (3) M. Laurie (31), 'On the 

 Morphology of the Pedipalpi.' Of these three authors only 

 the two last mentioned treated of the Phiynidfe. 



When we compare the ages of the embryos I intend to 

 treat about, we find that my first two are younger than 

 Perej^aslawzewa's youngest, my third one is of tlie same 

 age as her second, and my fourth corresponds to her third. 

 My fifth stage is younger than both Pereyaslawzewa's last 

 stage and Laurie's embryos. 



Preliminaey Remarks. 



I intend to divide the description of the embryos into five 

 parts, giving each stage in m}^ possession a section to itself. 

 In each stage I will first consider the general superficial 

 appearance, and then the details found in the sections. 



Stage I. 



The earliest stage at m^' disposal was obtained out of a 

 batch of well-developed eggs, the i-est of which had already 

 undergone reversion. The egg in question had for some 

 reason or other, probably pressure, stopped growing very 

 soon after fertilisation. 



It was perfectly spherical before being cut into sections, 

 and was enclosed in a loose outer membrane. Superficially 

 no differentiation whatever could be discovered. 



