THE CHIRONOM/IDA. 203 
the marine form by a light sea-green pigment. The mandibles and two pair of 
retractile hooked sucker feet are very similar to C. dorsalis, and I had, therefore, 
no <dloubt as to Compontia cruciformis of Johnston being a dipterous larva of the 
genus Chironomus, I found this larva several times on the Ode/ia zoophytes 
growing at the end of St. Anne’s pier, Next I found it on some Coryne fiom 
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 
Sick I sent my specimens, thought it would ultimately turn out that Johnston’s 
Compontia was Schiner’s 7halassomyia Frauenfeldi, 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.” 
He continues to say, after mentioning Mr. Ridley’s record* of 
this species at the Isle of Wight : 
**T 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 Compontia 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, These 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 Parthenogenesis in connection with 
C. dorsalis. One of the larvee, fully grown, was put ina 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 
Chironomus 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 pupze of Chironomus laid the eggs prepared in the body of the larva, I 
watched the older non-parthenogenetic larvz 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 larve of C. 
dorsalis produced. It is possible that Professor Grimm’s young larve 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 cruciformis is shown to be the larva 
of a Chironomus, 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 Cecidomyiz, 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 
the Aupe produce ova parthenogenetically. This I had some doubts 
about, and on referring to Balfour’s ‘‘ Embryology ”{ I find it stated 
* Ent. Mag., 1884. 
+ ‘*Ungeschlechtliche Fortpflanzung einer Chironomus Art. u. deren Ent- 
wickelung aus dem umbefruchteten Ei.” Mem. Acad. Petersbourg, 1890. 
+ ‘*Comparative Embryology,” vol. i., p. 335. Balfour. 
