THE CHIRONOMID^. 173 



The alimentary canal can be seen through the body-wall, and 

 consists of the following parts : oesophagus, proventriculus, stomach, 

 and intestine. 



There is another curious larva C. stercorarius described by Walker,* 

 I have not had the opportunity of examining the species myself: 

 " The grub of C. {OrtJwcIadius) stercorarius inhabits horse-dung, and 

 has a fleshy leg on the under side of the first segment, which points 

 towards the head, and which it has the power of lengthening and 

 contracting. Its various serpentine contortions also assist it in 

 moving. When removed from the substance which constitutes its 

 food, it is enabled to regain it by leaping. Lying horizontally, it 

 brings the anus near the head, regulating the distance by the length 

 of the leap it means to take ; when, fixing it firmly, and then 

 suddenly resuming a rectilinear position, it is carried through the air 

 sometimes to the distance of two or three inches. It appears to 

 have the power of flattening the anal extremity, and even of render- 

 ing it concave, by means of which it may probably act as a sucker, 

 and so be more firmly fixable." 



From the mention of only one fleshy leg, I should imagine this 

 description is taken from an immature larva. C. plumosus and others, 

 when quite young, show that the tivo prolegs arise from a cleft down 

 the centre of a single protuberance. This point is well shown in 

 Grumm's figures of the species he made observations upon ; he 

 says : "The thorax on its ventral surface possesses a transverse fold, 

 which is divided in the middle by a deep furrow, and transformed 

 into a pair of clinging feet." There is little doubt that the single 

 proleg of stercorarius described by Walker is accountable for in this 

 way. The larvte of Tanypiis are built much upon the same type, 

 some living in stagnant water {T. viaculati/s), others in swampy 

 places, upon various water-weeds {T. vwnilis) almost as thin as a 

 hair. 



Pcedogenesis iri Chironomus. 



M. Oscar v. Grumm found that agamic reproduction takes place 

 amongst the Chiro?iimi, and observed it fully in one species, and also 

 the development from the unfecundated egg. The larvae which this 

 observer experimented with were clear and transparent, of a 

 yellowish tinge, with large head, a broad thorax, and 9-jointed 

 abdomen. The mouth armed with two pairs of strong jaws, the 

 lower forming an immovable lip. The thoracic part on its ventral 

 surface possessed a transverse fold, which is divided in the middle by 

 a deep furrow ; these eventually grow forward and form a pair of 

 * Ins. Brit., vol. iii., p. 151. 



