LARVAL HEAD OF SOME CHIRONOMIDAE — GOUIN 183 



fications. What strikes the student at first sight is the presence of 

 numerous straight spine-shaped elements of variable dimensions, with 

 one or two points ; this character is particularly distinct on the epi- 

 pharynx, the lacinia, and the labium (fig. 5 and figs, i, 4). This 

 prickly aspect is set off by the shape of the mandible with its long 

 terminal tooth, and chiefly by the premandible. The latter in Pj^o- 

 tonypus morio is a straight club-shaped sclerite; its inner edge is 

 furnished with a few short spines, and it ends in a rather stylelike 

 and lightly curved point. The articulation is subproximal, the tendon 

 being inserted on the internal extremity. This disposition of the 

 application points gives great force to the muscle, which is an adduc- 

 tor. Lastly, it is a remarkable fact that the pharyngeal musculature, 

 which is rather reduced in all the other forms, is in Protanypiis morio 

 very much enlarged and powerful and may contribute a great deal 

 to the ingestion of the prey. 



It is the general effect of these modifications affecting different 

 organs which creates the individuality of the buccal structure, be- 

 sides preserving the fundamental orthocladian dispositions of the 

 labral and epipharyngeal ornamentations, and the mandibular, maxil- 

 lary, and labial articulations. As the regimen of this species is well 

 known, thanks to numerous analyses of intestinal content, and as it 

 is known that it ingests its prey, one may deduce the correlations 

 which the regimen, ingestion, and anatomical structure must have. 

 In effect, the modifications of the orthocladian structural plan affect 

 the epipharynx, premandibles, labium, mandibles, and in a way also, 

 the hypochilum ; to these is added the strength of the pharyngeal 

 musculature. These modifications when taken all together form the 

 distinctive features of the carnivorous orthocladian structure. The 

 mandibular construction alone is not sufficient for deducing the regi- 

 men of the animal. 



THE STRUCTURE OF PODONOMINAE 



This group has been created and raised to the rank of subfamily 

 by Edwards and Thienemann; Zavfel (1941) has analyzed the rather 

 uniform labral structure of almost all known larvae. Lasiodiamesa 

 gracilis K.{=sphagnicola K.) and Trichotanypus posticalis K. have 

 been examined. 



The structure, particularly the hypochilum, mandibles, and maxil- 

 lae, is incontestably close to the orthocladian type. On the contrary, 

 very distinct differences are found in the labral and epipharyngeal 

 formations and clearly give an individuality to the Podonominae. 



