TITANOSOMA AND POLYMICRODON IN ENGLAND 1 65 



the middle being deeply excavated. It is therefore a circum- 

 stance worth noting, in conjunction with the relationships 

 already discussed between Polymicrodon and Macheiriophoron, 

 that it is perfectly possible to distinguish the two genera with 

 a lens at the first glance by the shape of the pleurotergites. 



I have not been able to recognise spermatophores with 

 certainty within the gonopods, but the anterior gonopods 

 appear to be specially adapted for the reception of such, since 

 on the one hand they can be clasped between the grooves and 

 the grapnel, and on the other hand they can also be secured 

 behind the syncoxite underneath the distal processes and 

 between the two rows of awns, in such a way that the parts of 

 the hinder gonopod-segment form an opposing bed. 



Distribution : The new locality for Polymicrodon latzeli in 

 the North of England is very noteworthy from the zoogeo- 

 graphical point of view, since this is the first time that a 

 Craspedosomid of " Atractosoma-habit" has been recorded 

 from the northern region affected by the Ice Age. This is by 

 far the most northerly record for any such Craspedosomid. 



Larvce of Polymicrodon : In my forty-fourth Diplopod 

 paper 1 I gave for the first time a key to the larvae with 23, 26, 

 or 28 abdominal segments, belonging to the genera Ceratosoma, 

 Machetriophoron, Orotrechosoma, Helvetiosoma and Craspedo- 

 soma. The larvae of Polymicrodon should be embodied in this 

 key, and the following therefore is a completion of it. 



The Polymicrodon larvae have no longitudinal black bands 

 on the back or low down on the sides ; the collum and lateral 

 keels are therefore not strikingly distinguished by their light 

 colour. The animals appear on the contrary for the most 

 part of a uniform grey or brown. All dorsal bristles long, 

 strong and hooked, the inner ones projecting over the hinder 

 border of the pleurotergite. On the upper part of the hinder 

 border of the segments the projecting tubercles are weak, and 

 are not associated near the middle line with any grooves, but 



1 Zur Kenntnis der Craspedosomiden-Gattungen Helvetiosoma und 

 Orotrechosoma. Zoolog. Anzeiger, June, 191 1, page 27. 



