BRITISH SPECIES OF THE ORDER SYMPHYLA 649 



of the posterior margin of the last dorsal scutum, will at once 

 separate this species from S. imiiiaculata. 



S. caldaria, as its name implies, is a hothouse species, and 

 is recorded by Hansen from tanbark in hothouses, Copen- 

 hagen, and from the Museum hothouses, Paris. 



In my old collection I had specimens clearly referable to 

 caldaria taken by myself in very warm hothouses at Wylam, 

 Northumberland, the Kew Gardens, London, and the 

 Botanical Gardens, Glasgow. 



Genus SCOLOPENDRELLA, Gervais, 1839.* 



Following the characters given for Scutigerella yve. find that 

 the species of this genus are as a rule smaller and more 

 slender, and have the first pair of legs rarely more than one- 

 half the length of the following pair,f more usually rudi- 

 mentary, consisting of a small wart-like protuberance without 

 claws • whilst none of the exopods are well developed. 



The hind margins of all the dorsal scuta but the last one are 

 produced into a pair of triangular plates, most of which are at 

 most only slightly broader than long, and all (except the last 

 pair) rather large. 



The front surface of the posterior pairs of legs is furnished 

 with very few setse. The cerci generally have stripes on the 

 terminal area, and as a rule have, in addition, raised transverse 

 lines on the most distal part outside this area. 



Hansen has divided this genus into three distinct groups, of 

 which the first and the third concern us as regards the British 

 species. 



The first two groups contain species that have the first pair 

 of legs composed of three free and distinctly articulated joints 

 (not including the trochanter), whilst the tarsus terminates in 

 two conspicuous claws. 



In the third group we find species in which the first pair of 

 legs are obsolete, each being represented by a rudimentary 

 wart-like protuberance without even claws. 



* Comptes-reudus de I'Academie dos Sciences, ix., p. 532, 1839, 

 t li, noiacantka, G-ervais, is an exception, 



