30 ARKIV FÖR ZOOLOGI. BAND 3. N:0 28. 



The genital shield has the same shape, viz. is broad and 

 has a square anterior edge. 



In 8. histricinus it is fused with the ventri-anal shield along 

 its base, in the tritonympha with the ventral (as the anal shield is 

 separate) shield; in 8. ursinus (Fig. 12.) it is demarcated from the 

 ventrianal, in Parantennulus from the ventral shield (as the anal 

 shield is free). The only essential difference between 8ejodes 

 and the other two forms is, that the first pair of legs are pro- 

 vided with claws, and that the femora II of the J* have secun- 

 dary sexual characters in form of the chitinous tubercles known 

 from other Parasitidse but on the other hand the ambu- 

 lacra are absent on legs I and the tarsi are provided with long 

 sense hairs as in AntennophorincE and the legs I are more slen- 

 der than the other, as in the AntennopJwrince. Besides, even 

 closely related genera differ in this respect. 



I therefore unhesitatingly place the genus Sejodes amongst 

 the Antennophorinse and consider it to be the most primitive 

 form of them yet known. 



From 8ejodes Parantennidus is easily derived through 

 total reduction of the claws and ambulacres of legs I, reduction 

 of the claws in connection with higher developement of the 

 ambulacres of legs II — IV and developement of appendages 

 even on the upper jaw of the chela and flattening of the body. 



The shape of the ^ geni tal shield is still the same as in 8e- 

 jodes, but there are two longitudinal ridges to be found on it. 

 (Fig. 13.) 



The next stage is represented by the tritonympha of Neo- 

 megistus, in which claws although rudimentary still are present 

 and the palps still have 5 free joints. The J genital shield has 

 the two longitudinal ridges known from Parantennulus, and 

 the anterior edge is divided into one larger median and two 

 smaller lateral lobes (Fig. 14.), the first indication of the divi- 

 sion of the genital shield in one median epigynial and two 

 lateral paragynial shields which in different degrees has taken 

 place in the other Antennophorince. 



From this type the other genera which all have three ge- 

 nital shields may easily be derived. 



They represent three different branches. The first one is 

 constituted by Physalozercon which exhibits a degeneration of 



^ Berlese calls the median shield »endogynium». From a compari- 

 son with the other forms it is however evident that it is homologous with 

 the epigynial shield. 



