374 NATURAL HISTORY OF AQUATIC INSECTS CH. 

 tail end. Ei^ht of these form a semicircle on the 



o 



dorsal side, and in their midst are two spiracular 

 plates, each bearing three spiracular openings. Four 

 others stretch horizontally along the chord of the 

 semicircle, and another pair lie one on each side of 

 the anus on the ventral side. 1 



A small Chironomid, probably ThalassomyiaFrauen- 

 feldi, is common on our shores. The larva has been 

 described by Johnston as an Annelid, under the name 

 of Campontia cruciformis. It closely resembles the 

 Blood-worm of our ditches, except that it has a green 

 instead of a red tinge. A specimen of the larva has 

 been dredged off the Isle of Man from a depth of 

 over ten fathoms, and Mr. Swainson has often found 

 them on Zoophytes upon the sea-shore at St. Anne's- 

 on-the-Sea. The flies are often plentiful on the edge 

 of the retreating tide.' 2 



Several species of the brilliant, raptorial Dolicho- 

 podidae (see p. 369) haunt the surf and breakers of 

 the sea-shore, where no doubt they find their prey. 



The Beetles of the sea-shore include a host of small 

 Carabidae, predatory Insects, which lurk under stones 

 or burrow in wet sand. The terrestrial species have 

 been known to enter water in pursuit of their prey. 

 Bertrand, for instance, observed Carabus clathratus 

 chasing aquatic Insects in water five centimetres 

 deep. 3 The Carabidae of the sea-shore usually under- 



1 H. Gadeau de Kerville, Soc. Entom. de France, Vol. LXIIL, 

 p. $2 (1894). The fly has not been reared from the larvae de- 

 scribed, but it is probably that of Actora aestuum. 



2 Swainson, Brit. Naturalist, June, 1894. 

 ,3 Quoted by Plateau, loc. 



