THE CHIRONOMJD.E. 203 



the marine form by n light sea-green pigment. The mandibles and two pair of 

 retractile hooked sucker feet are very similar to C . donalis, and I had, therefore, 

 no tloubt as to Contpontia cj-iiciforniis of Johnston being a dipterous larva of the 

 genus Chironoiniis. I found this larva several times on the Ohelia zoophytes 

 growing at the end of St. Anne's pier. Next I found it on some Coryne from 

 the Mumbles (Swansea), and more recently I dredged it from fifteen fathoms off 

 Spanish Head (Isle of Man) adhering to seaweed. Professor Miall, of Leeds, to 

 whom I sent my specimens, thought it would ultimately turn out that Johnston's 

 Coiupontia was Schiner's Thalassomyia Fraiieiifeldi. This seems very possible, 

 as the description is very similar, but Schiner gives no drawings of the larva of 

 this species in his ' Fauna Austriaca,' p. 596, vol. ii." 



Ke continues to say, after mentioning Mr. Ridley's record* of 

 this species at the Isle of Wight : 



"I feel sure it is the same fly I have seen more than once on our pier-end at 

 St. Anne's-on-Sea. I may add that Mr. Johnston's drawing of Componlia does 

 not show the two pairs of long tubular protuberances which the larva can protrude 

 from the tenth segment, though he mentions them in his description. Tliese are 

 shown, however, very clearly in the micro-photographs of my best mount of 

 Compontia. 



" In conclusion, I must not omit to tell you of what I feel sure is an instance 

 of the very interesting development known as Partliciiogoiesis in connection with 

 C. dorsalis. One of the larvK, fully grown, was put in a bottle late in October, 

 1891. It sickened and died, but from the decaying body came forth a large 

 number of young C. dorsalis, which ultimately became fully developed, though not 

 so large as the other imagos. The bottle containing them was in a cold room, and 

 they all appeared in the winter before the end of February, and so could not 

 possibly be hatched from eggs laid prior to October. I watched these most 

 sedulously throughout the pupa state, for they spun their pupa-cells on the under 

 side of leaves, and not in the mud at the bottom of the glass like the ordinary 

 Chirouoiitus dorsalis, waving their heads about in the curious way described by 

 Meinert (21). They did not assume the deep blood-red colour either, being nearer 

 the surface of the water. Finding that Oscar Grimm had recorded the fact that 

 the pupa; of Chironomus laid the eggs prepared in the body of the larva, I 

 watched the older non-parthenogenetic larvae most carefully when they emerged 

 from the larval state, and I must say nothing of this kind took place as far as I 

 could see, and during the following month there were no young larvee of C. 

 dorsalis produced. It is possible that Professor Grimm's young larvae were 

 parthenogenetically reproduced." (G. Swainson, F.L.S., 1892 ) 



These notes are extremely interesting, not only on account of the 

 fact that Johnston's Compontia criiciformis is shown to be the larva 

 of a ChironoiHus, but also as showing what is an unusual character 

 in Parthenogenesis. Parthenogenetic reproduction, as a rule, takes 

 place in the summer months, as seen in the Aphides, Crustacea 

 ( Daphnia), and Cecidomyias, where we see the asexual reproduction 

 taking place during the summer, and at the approach of cold 

 weather the process of ovation taking its place. In regard to 

 Oscar Grimm's observations, I have not had the opportunity of read- 

 ing his original paper,! but the translation into English states that 

 ihepnpcr produce ova parthenogenetically. This I had some doubts 

 about, and on referring to Balfour's " Embryology "J I find it stated 



* Ent. Mag., 1884. 



t " Ungeschlechtliche Fortpflanzung einer Chironomus Art. u. deren Ent- 

 wickelung aus dem umbefruchteten Ei." Mem. Acad. Petersbourg, 1890. 

 X "Comparative Embryology," vol. i., p. 335. Balfour, 



