GyrinidcF.] auepiiaga. 211 



and the Brachelytra ; the question must be left an open one, but for the 

 present it seems best, considering the evidence, not to separate them 

 from the Adepliaga ; it is quite probable, when we remember the com- 

 paratively recent discovery of AwjMzoa by ]\Ir. INfatthews, that further 

 connecting links may be discovered which will settle tlic question ; no 

 series can be stamped once for all as finally completed ; the Paussidai 

 among the Clavieornia show some strong affinities with the Adephaga, and 

 in other families more or lest distant relations with the same series may 

 be o1>served. The chief work on the group is tlie " ]Monogra])hie des 

 Gyrinida}," by M. Regimbart, publislied in the Annales de la 8oc. Ent. 

 Fr. for 1882-83 ; as there constituted, the Gyrinida» contain nine genera 

 and about two hundred and seventy species ; two of these genera occur 

 in Europe, both of which are British ; they may be distinguished as 

 follows : — 



1. L.ibrum transverse, not prominent; upper surface not 

 pubescent, punctured in rows ; last abdominal segment 



rounded and depressed Gthinus, Geoff. 



2. Labrum semicircular, projecting; upper surface with 

 tliick short pubescence, irregularly punctured ; last 



abdominal segment elongate and not depressed .... Oeectociiilus, Lac. 



GVRINUS, Geoffroy. 



About seventj'' species are contained in this genus, which are widely 

 distributed throughout the world ; they are usually fouml in large grou])S 

 on the surface of the water, on which they move very swiftly, so swiftly 

 in fact, that, when disturbed, the eye can hardly follow their motions ; 

 on the approach of danger they usually dive below tlie surface, but 

 soon reappear ; they are among the most familiar of the Coleoptera to the 

 ordinary observer, and are commonly known by the name of " whirli- 

 gigs " or " steel-coats ;" they have in most instances the power of 

 secreting a milky fluid with a disagreeable odour of apples ; they are 

 usually of a brilliant bluish-black or steel-black colour above with the 

 rows of punctures reflecting a bright brassy tint ; some species, however, 

 are duller, and the females, as a general rule, are duller and larger than 

 the males ; the males have the whole of the five joints of the anterior 

 tarsi dilated and furnished beneath with a large number of little round 

 transparent suckers (about fifty on each joint) whicli form a very beau- 

 tiful object under tlic microscope ; the GyriniiUv, like the Dytiscidie, 

 have ample wings, and can fly from one spot to another, when their 

 native pools dry up ; hence their sudden appearance on newly formed 

 pools and puddles. 



The larva of Gyrinus is as curious as the insect itself; it is figured in Westwood's 

 Class:ticati(m, vof. i., p. 100, Kig. H, 18, and also by Sclii.idtc, Nat. Tids. i., 1*1. iii.. 

 Fig. 1 : it is chiefly remarkabh' for the long slender, transparent and meml)rauous 

 fdanients which arise from each side of tlie nine abdominal sognunts, the terminal 

 joint being furnishtd with two pairs, and tlic eight preceding witli one pair each ; thrv 

 are fringed with hairs, and are employed as organs of re5i)iration ; the larvaas a whole 

 is long, nariow and compressed, and resembles closely a small centipede; it is wiiitish, 



