8 Psyche [February 



tendons, at the posterior ends of which are the retractor muscles 

 (shown broken oflf in Fig. 126), attaching to the occiput on each 

 side of the occipital foramen. 



The muscles of the maxillary setse are much more powerful than 

 the mandibular mus<jles. The protractor muscles (Fig. 126, 'pmf') 

 attach to the maxillary plate (Fig. 10, mxp). In the drawing 

 they are shown slightly curved, to avoid confusion with other 

 parts, but in reality they are practically straight. The retractor 

 muscles attach to the occiput on each side of the occipital foramen. 

 Passing forward between the plates of the tentorial structure 

 (ts), (where the mandibular setse lie on a slightly higher plane 

 than the maxiUary) the pairs of setse on either side of the pharynx 

 approach closer together and pass between the struts (Fig. 11, 

 ts^ and ts^) from the pharynx and the base of the labium, run 

 alongside and partly beneath the hypopharynx, and descend 

 over the base of the labium (bl) into the rostrum. Soon after 

 entering the rostrum, the maxillary setse close together and 

 interlock (Fig. 13 max s), forming an air-tight tube. The tips of 

 the maxillary setse are acute and smooth. The tips of the mandi- 

 bular setse are flattened and acute, and numerously and minutely 

 barbed on the outer sides, the barbs pointing backwards. The 

 tips of both pairs of setse are practically without curve. The 

 mandibular setse are quite free from the maxillar setse, though 

 they lie close on each side of the former in the rostrum. 



That the maxillary setse form an air-tight tube can easily be 

 seen under a fairly high power, when liquid food and bubbles of 

 air can be traversed from end to end of the tube by pressing with 

 a needle. The maxillary setse or sucking-tube can be protruded 

 far beyond the tip of the rostrum, whilst the mandibular setse 

 can be protruded only slightly. The latter are used to pierce 

 the prey, and retain it in position by means of their barbed tips, 

 whilst the maxillary setse forming the sucking-tube are probed and 

 extended into every part of the body where there are any juices. 

 It seems probable, also, that the sucking-tube is used to conduct 

 the poisonous saliva from the syringe into the wound madein 

 the animal attacked. On attacking any animal the bug probably 

 slightly protrudes the tips of the setse and contracts the muscles 

 at the end of the rostrum, the latter thus closing on and holding 

 the tips of the setse firmly. The animal is then pierced and securely 



