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ventral sclerite of the head capsule. The base of the hypopharynx 

 carries a strong median tooth (T) which works against teeth 

 on the inner (ventral) aspect of the labrumi, as in Helodes and 

 Dascillus ; the vertical masticatory action which apparently 

 takes place in these larvas is remarkable. Just in front of this 

 tooth, on each side of the base of the hypopharynx, projects a 

 prominent condyle (co), against which rests the base of the 

 maxillula (Mx). The maxillula consists of an outer lobe with 

 blunt apex (in the Helodes larva this is acuminate) and beset 

 with numerous rows of minute spines, many of which are comb- 

 like, having three or four blunt denticles (A). Ventral to this 

 lobe the maxillula is prolonged into a somewhat acuminate 

 condyle (co') into which is inserted a delicate muscle arising 

 from the condyle (co) of the hypopharynx. The inner edge 

 of the maxillular lobe is beset with a series of 30 to 40 delicate, 

 flexible spines (t) ; the corresponding spines on the maxillula 

 of the Helodes lai'va are fewer and stronger. Internal to these 

 a curved row of eleven stout, prominent teeth (tt) is conspicuous. 

 A homologous row of similar teeth in the larva of Helodes was 

 believed by Miss MacDowell and me to belong to the hypo- 

 pharynx, not to the maxillula. In the larva now under ex- 

 amination, however, there lies internal to this row of teeth a 

 delicate but perfectly definite edge (e), beset with numerous 

 fine hairs, and united basally with the central sclerite of the 

 hypopharynx. The position and appearance of this edge 

 suggest that it is really the inner margin of the maxillula ; if 

 so, the strong teeth (tt) must be regarded as borne on the latter 

 organ. 



The larvae of the Dascillidie and Scarabaeidas already de- 

 scribed have the mouth-parts — as in the great majority of 

 beetle-grubs — adapted for biting solid food. It is noteworthy 

 that Mangan has lately (1912) recorded the presence of maxillulas 

 in some larvae of the carnivorous water-beetles (Dyticidœ) — 

 Dyticus and Ilybius — which have the mandibulate mouth 

 specially modified for taking food by suction. In these insects 

 the maxillula consists of a small pointed or rounded prominence, 

 situated internal to the mandible and dorsal to the maxilla. 

 In Dyticus at least it is far removed from the labium or the 

 hypopharynx. I have made a preliminary examination of 



