AN U RID A. 



357 



last abdominal segment is terminated either by caudate 

 or forcipate appendages. A ventral tube is never present. 

 The mouth-parts may, or may not, be sunk within the 

 head, the nervous system consists of a brain and ten 

 or eleven ventral ganglia, and Malpighian tubes are 

 generally present. 



The relations of the Collembola to the rest of the 

 Insecta are shown in the table on p. 358. 



The Collembolan described in the present Memoir is 

 a convenient insect to study, as it can be obtained in 

 plenty in various localities scattered around the coasts of 

 the British Isles. According to Plateau it was first 

 discovered in Denmark by Strom, who named it Podura 

 ambulatoria cauda carens. It was afterwards found in 

 Normandy by Gruerin-Menneville, who, in 1836, re-named 

 it Achorutes maritimus ; Nicolet, however, refers to it as 

 Anoura maritima. In 1864 Laboulbene erected for its 

 reception the genus Anurida, but in Lubbock's " Mono- I 

 graph of the Collembola and Thysanura " it is described 

 as Lipura maritima. At the present day its nomenclature 

 has become settled, and it is now universally known as 

 Anurida maritima. 



Those who have not the opportunity of working at the 

 sea-side can use with advantage the common Podura 

 aquatica as a substitute for Anurida. Podura is a very 

 plentiful species in many parts of Britain, and is to be 

 sought for on the surface of the water of wayside ponds 

 and ditches. 



II. BIONOMICS. 



Anurida maritima is a dark blue-black insect measur- 

 ing 2-3nim. in length. The individuals seen in fig. 2 show 

 the general appearance of the species to the naked eye, and 

 will aid in recognising it as it crawls about on the sea-shore. 



