220 



PSYCHE. 



[July, 190 1 



The first abdominal ganglion is the 

 last of the chain to be represented and 

 tends to unite with tiie ganglion of the 

 preceding segment. 



As all these generic characters appear, 

 not only in the two species of Neelus 

 found by me, but also m. Alegalofhorax 

 minimus Willem, the latter (and later) 

 genus falls. N. minimus, unlike the 

 other two species, has three pairs of 

 small cuticular cupules, and the attitude 

 of the head, as figured by Willem, is 

 more nearly vertical — an attitude, how- 

 ever, that occurs at times in the other 

 forms ; finally, the segmentation of the 

 body (obscure in murinus and minutus) 

 is pronounced in minimus — a difference 

 also found within the allied genus 

 Sminthurus. With this last genus, Nee- 

 lus should be compared, although it may 

 be stated at the outset that the differ- 

 ences between the two are much greater 

 than those that separate Sminthurus 

 and Papirius. 



As contrasted with Sminthurus, then, 

 the head of Neelus is articulated by its 

 entire base, without a projecting vertex, 

 higher than the neck. The antennae, 

 in particular, instead of being longer 

 than the head and slender, are but half 

 as long as the head and have stout seg- 

 ments, the last of which is not annulate, 

 as it is frequently, although not always, 

 in Sminthurus. The thorax, far from 

 being condensed, with the legs brought 

 together, is much more extensive than 

 the abdomen — an essential difference 

 • — and the legs are well separated. 

 The metathorax is remarkably long and 



the coxae as well. Again, the ventral 

 tube is long, of peculiar form, and does 

 not extrude long filamentous tubes. 

 There is no prominent anal tubercle in 

 Neelus. The stomach is divided into 

 spherical compartments, instead of being 

 cylindrical as in Sminthurus. Other 

 differences, of minor importance, exist 

 but need no mention. 



Neelus should, however, be assigned 

 to one family with Sminthurus and 

 Papirius, notwithstanding my earlier 

 opinion, and clearly becomes the most 

 primitive genus of Sminthuridae. In 

 Willem's (1900, p. 67) words: 



^^ lilegaJothorax [Neelus] est un Smintliuri- 

 de qui a conserve les caiactferes arcliaiques 

 siiivants : 



1. la forme des antennes; 



2. le de\eIoppement du thorax, dont seiil 

 le pi'emier aniieaii a siibi une legerc regres- 

 sion ; 



3. la persistance trfes nette de la segmenta- 

 tion abdominale; [this applies to species 

 iniuhniis only, at present.] 



4. la nettete des deux articles precoxiens 

 de's pattes ; 



5. la simplicite dc 1' appareil reproducteur 

 ni&le. 



C'est done, sons hien des rapports, le phis 

 archaique des Sminthiirides : il s'est separe 

 de la souclie du groupe a\ant Prosminihuyus 

 [of Willem] et Smiuthutus.. 



II offre comma specialisations secondaires: 



a. la disparition des yeux ; 



b. les trois cupules sensorielles ; [applies 

 to minimus only.] 



c. la diminution de volume de I'abdonien, 

 plus ramasse que chez SmiiitJiinns ; 



d. r absence d' appareil trach^en ; 



e. la structure speciale de I'intestin niov- 

 en." 



The break between the Smintliuridae 



