618 



SIR JOHN LFBBOCK ON 



Two teeth to the mucrones. 



Isotoma bidenticulata, Tullb. 

 ,, grisea, Lubbock. 

 Three teeth placed one after the other. 

 Isotoma tigrina (Nicolet). 

 ,, grisescens, SchaflPer. 

 ,, maritima, Tullb. 

 ,, longidens, SchafFer. 



Figs. 1-7. 



Isotoma spitzbergenensis. 

 1. Side view of head. 2. Side view of foot. 3. Foot seen from above. 

 4. The spring. 5. Side view of same. 6. Tip of same, more magnified. 

 7. The catch. 



The new species agrees with the last four in the above table 

 in the possession of three teeth in the mucrones ; but it differs 

 from them by having two of the teeth at the base, and also by 

 the form of the mucrones. The only two remaining species with 

 which it should be compared are /. minor, Schaffer, and I. nota- 

 hilis, Schaffer. I. minor * has the dentes of the spring 2| times 

 as long as the manubrium, and the fourth segment of the 

 antenna is also longer than the third, I. notaiilisf also has the 



* Schaffer. " Die Collembola der Umgegend von Hamburg," Mitt. a. d. 

 Naturh. Mus. Hamb. vol. xiii. 1895 (1896), p. 179. 

 t Schaffer, ibid. 



