80 Mr. R. S. Bagnall on 



colour, being devoid of pigment. They have thirty body- 

 segments, the lateral keels are weakly defined, and the ocelli 

 few in number, usually indistinct and poorly pigmented. 

 That they are clearly of Chordeumid (s. 1.) affinities may be 

 recognized on the field. 



The members of the genus are to be found on the ground 

 surface beneath shallow coverings of fallen leaves or under 

 stones, sheltering in crevices or about the roots of vegetation. 

 If found on the surface of the earth or perhaps on the under 

 surface of the upturned stone, they usually remain quiet for 

 some little time, and will then, or if but slightly disturbed, 

 run away with a quick gliding movement. If less mildly 

 disturbed, or touched for instance by the dead leaves one may 

 be removing, they will quickly curl up, and, the conformation 

 of the ground being suitable, roll away. 



The best time to search for these animals would seem to 

 be from the early spring (say, March) to May, and again in 

 the late autumn. , 



Although we now know four species of Brachychceteuma, 

 the genus is only of recent discovery. The first species and 

 type of the genus and family, Brachychceteuma bagnalli y 

 Verhoeff, was described in 1911*, and in greater detail the 

 following year "j", from a single male example collected by 

 the writer in Gibside, a fine old piece of woodland in the 

 county of Durham. 



Until 1917, when Dr. Hilda and the Rev. S. Graham 

 Brade-Birks diagnosed Brachychceteuma bradece (Brol. et 

 Brade-Birks) J from Lancashire (examples of both sexes 

 having been secured), no further discoveries of the group had 

 been made. They referred this species to a new genus — 

 Jacksoneuma, — but upon the rediscovery of Brachychceteuma 

 bagnalli, as detailed below, Verhoeff's description of the 

 genus proved to be at fault in three important particulars, so 

 that the genus Jacksoneuma, the erection of which was fully 

 justified upon the data at that time available, had to be 



* Verhoeff, K. W., " Ueber Brachychceteuma, n. g., und Titanosoma 

 juratsicum aus England," Zool. Anz. xxxviii. pp. 455-458, Nov. 14, 1911. 



f Verhoeff, K. W., " On the Occurrence of Brachychceteuma, Titano- 

 soma, and Polymicrodon in England," Trans. Nat. Hist. Soc. Northd., 

 Durham, and Newcastle, n. s. iv. pp. 143-167, pis. ix. & x., June 1912. 



Bagnall, R. S., " Brief Records of Chcetechylene vesuviana, Newp., and 

 other Myriapods new to the British Fauna," The Zoologist, xvi. pp. 264- 

 266, July 1912. 



% Brade-Birks, Hilda K. and Rev. S. G., " Notes on Myriapoda.— VIT. 

 u A new Member of the Order Ascospermophora {Jacksoneuma bradece, 

 gen. et sp. nov.)," Journ. Zool. Res. ii. pp. 135-149, figs., Dec. 1917. 



