128 Dr. M. Laurie on the 



basis Pocock's classification *. I have enclosed in parentheses 

 the names of those genera which I have not had an oppor- 

 tunity of examining, and their position is in some cases 

 doubtful. So far as observation has gone the members of 

 the family ScorpionidjB are all characterized by the katoi- 

 kogenic mode of development, the other families — Turidge, 

 Bothriuridge, and Buthidai — being apoikogenic. 



Fam. I. Scorpionidae. 



Subfam. 1. SconpiONiNi. 



Scorpio J [Heterometrus), [Micephonus) , {(Ecopetrus), Opisth- 

 ophthalmus, Palamnceus. 



In this subfamily the chelicerge masticate the central cord 

 and there are dorso-lateral outgrowths from the free segments. 

 The lung-book lamellae have spiny free margins. Opisth- 

 ophthalmns might be erected into a separate subfamily on the 

 strength of the extraordinary outgrowths from the carapace 

 and prostomium. Scorpio^ however, shows an approach to 

 the proatomial outgrowth. 



Subfam. 2. Tscsnurini. 



IschnuruSj (Opisthacanthus), Opisthocentriis^ (Cheloctonus) ^ 

 {Chiromachus) . 



In this subfamily the chelicerge send root-like processes 

 forward into the appendix, as described above. The linig- 

 books are spinous. This is Pocock's subfamily minus Ilor- 

 murus and lomachus, along with which some of the other 

 genera ought possibly to go. 



Subfam. 3. ITommurini, nov. 

 Ilormurus, {lomachus). 



The characteristic feature here is the absorption of nourish- 

 ment by the chela3, as described above. The lung-books ai-e 

 spinous. lomachus seems, from Pocock's description, more 

 closely allied to Hormurus than to the Ischnurine series. 



Subfam. 4. Diplocbntrini^ Pocock. 



Diplocentrus^ {Otclus), Nebo, [Cyphocentrus) . 



Nothing is known in this subfamily of the later embryonic 



* Ann. «fc Mag. Nat. Hist. ser. 6, vol. xii. Kraepelin's arrangement 

 (Hamb. \Mss. Anst. 1890 and 1893), -which is later, is almost identical as 

 regards the main groups. 



