Anatomy of some Scorpions. 193 



(1) Scorpio, Heterometrus, Opisthophthahnus, Palamnceus, 



Opisthccentrus, and Hormurus remain associated as 

 one group on the ground of their embryology. 



All the rest have the Euscorpius type of develop- 

 ment, and can be divided by their lung-books. 



(2) A second group is formed by Scorpiops, Vejovis, Ha- 



drurus, Broteochacias, and Bothriurus, which have 

 " spinous " lung-books. Vejovis may have to be 

 isolated on account of the difference in development. 



(3) Diploceittrus, Nebo, Iurus, and Euscorpius agree in 



having the arcade type of lung-book. 



(4) Buthus, Parabuthus, Uroplectes, and Centrurus have 



the reticulate type. 



The first and last of these groups are in perfect accord, so 

 far as they go, with Pocock's classification ; the others agree 

 less perfectly. The separation of Euscorpius from Broteo- 

 chactas is not improbable, and gets over the difficulty of the 

 geographical distribution of the Chactini ; but the association 

 of it with lurus, and still more with Diplocentrus and Nebo, 

 is less plausible, and it is much to be regretted that I have 

 had no opportunity of examining the ovaries of these last two 

 genera. 



The bringing together of Bothriurus and Hadrurus is not 

 unnatural. Pocock says of theBothriuridas: — "The Scorpions 

 of this group seem to be little more than an exaggeration of 

 some of the American members of the Iurini, for some of them 

 show many points of resemblance to Caraboctonus and Ha- 

 drurus.'" Unfortunately the two forms here named do not, 

 according to the lung-books, seem to be closely related. 



Kraepelin's * classification needs less alteration, inasmuch 

 as he unites the Iuridse and Scorpionidae of Pocock as one 

 family. His subfamilies are practically the same. 



How far these internal characters will agree with the ex- 

 ternal ones when these last are re-examined is a question 

 which I think it better to leave to those who have had 

 experience in discriminating the minute points of external 

 difference. 



EXPLANATION OF PLATE IX. 



Figs. 1-5. The abdominal nervous system. 

 Fig. 1. Pambuthus capensis, X -f. 

 Fig. 2. Palamnceus Thorellii, nat. size. 



* Jahrb. Hamb. Wissen. Anstalten, xi. 1. 



