Septembkb, 1901.] 



KNOWLEDGE. 



197 



in tlie £;re<nt divergence between the two sexes, tho male 

 having^tlic nsual faeics of his genus, while the female 

 in some respects seems to approach C^lunio— perhaps 

 the most characteristically m;uinc member of the 

 whole order. 



The male (Fig. 7) of Cliini'i imiriniix was dcseribcdtt 



FlQ. 'J. 



Fig. '.— Chinio marinns, male (side view). Fig. 8 — Female 

 (uuder view). Fig. 9. — Larva (side view). Maguitied 24 times. 



forty-six years ago by thai admirable Irish entomologist 

 A. H. Haliday, who found the insect in Co. Kerry " on 

 gravelly sea-coasts below high-water mark, walking with 

 the wings half-raised, and in rapid vibration without 

 taking flight." Clunio is readily distinguished from 

 Chironomus h\ the degeneration of the jaws being 

 carried to an extreme point; only four minute hairy 

 tubercles, representing apparently the lol>es and palps 

 of the second maxillje. can be made out. The eleven- 

 segmented feelers of the male are most characteristic in 

 form ; the head is almost entirely hidden beneath the 

 great hood-like forebody shield, while the hinder end 

 of the insect seems disproportionately large owing to 

 the immense size of the genital cla-spers. This midge is 

 only about 2 mm. long. 



" I have observed the insects," wrote Haliday, " only 

 in blustery weather, and could not find any trace of the 

 female among them.' She escaped observation indeed 

 for well-nigh forty years; then in 1894 descriptions 

 of her were published almost simultaneously || by 

 M. Rene Chevrel, who had been diligently studying the 

 species along the rocky coEists of Calvados, and the 

 present writer, who met with a colony on the shores of 

 Killiney Bay, Co. Dublin. The female Clunio (Fig. 8) 

 is wingless and degraded — almost worm-like with her 



+t A. H. Haliday. "Descriptions of the Innects fisured. &c ." 

 yat. Hist. Rev., Vol. II.. 1858 {Proc. of Hoc, p. 62). 



XX K' Chevrel. " Sur un Diptcre Marin du Genre Clunio." 

 Arch. Zool. Exp Gen. (3) 11., 189i, pp. .58,3-598. ft H. Carpenter. 

 "Clunio marinus, a Marine Chironomid." Enl. Mo. Mng., 

 Vol. XXX., 1894. pp. 120-30. J. J. Kieffer. " Description d'un 

 Diptere sous luariu." Bv.V. Soe. En(. France, 1898, pp. 105-8. 



elongatAj and (when full of eggs) swollen hind-body, her 

 short and feeble legs, her feelers with only seven reduced 

 segments, and her small eyes. 



According to M, Chovrel's obsci-vations, Chuiio can 

 only be observed during the low spring tides, " One 

 only begins to see them,' he writes, " when the rocks 

 where they dwell are uncovered. Few in number the 

 lii-st day, tliey abound on the morrow and the two 

 following days. Then, becoming scarcer and scarcer, 

 they disappeai- completely towards the sixth or seventh 

 day, not to be seen again till the next syzygy," Thus 

 periodically they appear from April till October. Tho 

 males aie very active, moving over the rocks and the 

 seaweed — frequenting especially the masses of the bright 

 green Cladophora- or skimming across the surface of 

 tho rock-pools. They ;u-e in search of tho females who 

 creep slowly about among the seaweed. When mating 

 takes place, the male seizes the female with his powerful 

 clampers, holding her by tho last abdominal segment, 

 and carries her away with him, her body being almost 

 in a line with his, and her feet, clear of the surface 

 whereon he is walking, kicking in the air. " lie takes 

 her about thus for an hour, " states M. Chevrel, " then 

 he places her on a rock or an alga. The female, being 

 freed, walks slowly for some minutes, and chooses a 

 suitable spot to lay her eggs. ... She applies the 

 tip of her abdomen to the rock or seaweed and fixes 

 thereto a gelatinous, cylindrical tube wherein the eggs 

 are lodged. " These number from 50 to 120. " When 

 the operation is finished, the female, exhausted by the 

 efforts which she has made, can only move slowly; she 

 walks painfully, stops often, and only regains a little 

 strength after" resting for several minutes; then she 

 wandei-s at random and ends by falling into the water, 

 and, floating on the surface, waits for death, which is 

 never long delayed." Often her feet become caught in 

 the gelatinous substance of her egg-tube; she fails to 

 disengage herself and dies resting on her eggs. " The 

 male who has fertilised her," writes M. Chevrel, with 

 a fine appreciation of this little drama of love and 

 death, '' does not forsake hei- ; he stays near while the 

 o^ggs aro being laid, then, as if he knew his duty as 

 husband or father, lie throws himself upon her to 

 rescue her from the sticky substance, or to carry her 

 with her eggs to a more favourable place for the hatch- 

 ing of the ofispring. Sometimes he falls himself a 

 victim to his devotion and dies beside his mate, taken 

 in the same snare." 



The shrinkage of the female's body after the eggs 

 have been laid is most remarkable. The degradation of 

 the jaws in both sexes is such as to render feeding 

 impossible, so that Clunio is an excellent example of 

 those insects in which there is a complete division of 

 labour between the larval and perfect stages of the life- 

 history, the former only being concerned with feeding 

 and the latter entirely devoted to reproduction. Tho 

 life of Clunio as a midge is therefore very short. 

 M. Chevrel could find no trace of them after the tide 

 had covered their breeding-places, and doubts whether 

 they survive either by coming to the surface, or by 

 seeking shelter below. But as he was able to keep 

 specimens alive for 36 hours in captivity, it is likely 

 that they survive from one low tide till the next — • 

 especially as a Clunio was discovered in the Adriatic 

 at Trieste among submerged colonies of mussels. 



The lai-va of Clunio is hatched about a week after 

 the eggs ai-e laid, being then only I mm. long, whitish 

 and partly transparent. Tho full-grown lai-va (Fig. 9) 



