1894-] ENTOMOLOGICAL NEWS. 215 



tion of these appendages is the Archeidae. Two pairs of appen- 

 dages in Arachnidu function as mouth-parts and four as legs; yet 

 in some forms, as Solpugida, Thelyphonida and Phrynida, the 

 first pair of legs serves the purpose of antennae, and are structu- 

 rally different from the other pairs. 



Within the Arachnida Prof. Kingsley recognizes the following 

 orders in the order mentioned : Scorpionida, Thelyphonida, 

 Araneida, Solpugida, Pseudoscorpii, Phalangida, Acarina. I 

 don't suppose that this is a lineal arrangement, but rather from 

 the Scorpionida to the Araneida, and from the Solpugida to the 

 Acarina. The Phrynida should rank as a separate order, for they 

 are fully distinct from the Thelyphonida as from the Araneida. 

 Two lines of development can be traced in the Arachnida, the 

 sternal and the asternal. The latter is the earliest and embraces 

 the Scorpionida, Pseudoscorpionida, Solpugida, Acarina and 

 Thelyphonida; the former the Phrynida, Phalangida and Aran- 

 eida. The primitive Acarina (Eupodidae) are asternal; and, 

 besides the absence of cephalic segmentation, there are no im- 

 portant characters to separate certain Eupodid genera (Erynetes, 

 Rhagidia) from the Solpugida. The Phalangida plainly came 

 from the Pseudoscorpionida through such forms as Siro. The 

 Araneida of course came from the Phrynida. The relation of 

 the Scorpionida to the ancient Eurypterids is pointed out by 

 Prof. Kingsley, and clearly indicates the origin of the Arachnida 

 irom that group. The Eurypterids and Trilobites have had a 

 common stem leading back to the Diplopods, and the Trilobites 

 bear about the same relation to the Crustacea that the Eurypterids 

 do to Arachnida. 



The appendages of the Crustacea I would homologize as fol- 

 lows: Three pairs of appendages has the typical Arthropod head, 

 no more. The Isopods have a pair of mandibles and two pairs 

 of antennary appendages; directly behind the mandibles is the 

 lower lip, this indicating the end of the head. The other mouth- 

 parts are cephalized thoracic legs. Where are the maxillae of 

 Diplopoda ? By the process of cephalization the thoracic seg- 

 ments and their appendages have crowded the maxillae to one 

 side and in front, and they appear as the second pair of antennae; 

 the antennules of Crustacea being the true antenna*; and instead 

 of believing that in several groups of Arthropoda one or two 

 pairs of cephalic appendages have disappeared and left not even 



