Crop in the Mallophaga. 269 



Amblycera. 



Heterodoxus longitarsus (Piaget) (fig. 3). — Tlio crop is 

 rather small, and the ventriculus, which follows, is parallel- 

 sided, without anterior cseca. The teeth, situated in front of 

 the opening into the ventriculus, point backwards, and are 

 rather long, tapering, fairly broad, and numerous, arranged 

 in a single row. In Trimenopon echinoderma there is a row 

 of teeth of similar shape in the same position. But poste- 

 riorly there lie two chitinous flattened lobes, the free ends of 

 the flaps being anterior and the two flaps being side by side, 

 with a narrow longitudinal space between. The free pro- 

 jecting edges of the flaps possess a single row of minute 

 denticles. 



Lcemobothrium titan, P. — The teetli are here grouped in 

 two brush-like patches, one on each side of the base of the 

 crop. The teeth are long, thin, round, acicular, curved, 

 and closely set. 



Trinoton luridum, N. — The teeth in this species are more 

 developed than in any other genera I have examined up to 

 the present. Seen in situ they please the eye with their 

 beautiful symmetry of arrangement and their sabre-like 

 shape. As usual they consist of a single row situated around 

 the base of the crop, rather densely packed and of a dark 

 brown colour. Each tooth is long (about *14 mm.), curved, 

 flat, blade-like, parallel-sided, and at the base has a back- 

 wardly projecting sharp spur, which no doubt constitutes the 

 place of attachment of. the tooth to the lining of the crop. 

 Just behind the row of teeth there are two patches, one on 

 either side, of scattered teeth of quite a different character. 

 These are long, curved, and round, of a white-coloured chitin. 

 The rest of the crop shows numerous minute scattered bristles 

 or teeth of a clear white chitin, the bases of which appear to 

 be forked, suggesting sponge-spicules. 



Function. 



Plateau, who was able to speak with authority on the 

 digestive arrangements of insects, formed the opinion that 

 the proventricular teeth are used for straining rather than for 

 masticating food. In the Amblycera it seems improbable 

 that the teeth have any masticatory function, as they are 

 long, slender, and sharp, and their development is not corre- 

 lated with powerful muscular folds. In the Ischnocera the 

 short scattered teeth may be of assistance in clearing out the 

 food which collects in the anterior caecum, where they are 

 situated. 



