180 MR. A. E. CAMEROX ON 



muscles. In the first case a single branch is given off from the 

 main fibre and may be traced to the surface of the pear-shaped 

 dilatation ; in the second case two branch fibres may be supplied, 

 one from each of the two nearest longitudinal muscles. Under a 

 nerve stimulus these branches are said to be the mechanism 

 whereby the mid -gut appendages are animated with a movement 

 analogous to that observed in the case of the Malpighian tubes 

 (Sinety [1901]). 



In the anterior region of the mid-gut there is a distinct dorso- 

 longitudinal furrow (PI. XXYIII. fig. 1, F, and fig. 3, FJ in 

 which numerous longitudinal muscles are congregated, and to a 

 less extent the same phenomenon is observable in the ventro- 

 longitudinal fuiTow. The fibres which are situated dorsally 

 and laterally on the mid-gut are united into three, then into 

 a, single strand which proceeds anteriorly to its attachment in 

 the pronotum. Those fibres lying ventrally are united into a 

 somewhat more slender strand. 



As they pass backward to the hind-gut the longitudinal 

 muscles become grouped into six strong bands applied symmetri- 

 cally to the wall of the gut, and giving off distally cutaneous 

 branches which proceed outwards. 



Summary. 



The alimentary canal of B. rossii presents us with much that 

 is of interest. Its rectilineal shape is what we would naturally 

 expect from the narrow elongated form of the insect. But the 

 absence of a gizzard, together with the rudimentary digestive 

 cfeca and the presence of tvibular filiform organs at once arrest 

 attention. The anterior portion of the mid-gut is puckered owing 

 to the isolation of the circular muscle-bundles. The Malpighian 

 tubes are curiously grouped in bundles of from three to six, each 

 bimdle opening into the gut by a common duct. The small 

 intestine is sejDarated from the rectum by six jDowerful pyramidal 

 valves. The internal wall of the crop telescopes into the lumen 

 of the mid-gut, and the telescoped portion is reflected on itself in 

 a curious manner. 



The fact that the males of B. rossii are disappearing points to 

 parthenogenesis not being the primitive method of reproduction, 

 but suggests that the species has become adapted to it through 

 the failure of sexual reproduction. 



Literature. 



1841. DuFOUR. — Recherches anatomiques et physiologiques sur 



les Orthopteres, les Hymenopteres et les Nevropteres. 



Mem. Ac. Sc. Paris, t. viii. p. 265. 

 1858. SiRODOT. — Recherches sur les secretions chez les insectes. 



Ann. Sc. Nat. (4) t. x. p. 251. 

 1875. Plateau. — Recherches sur les phenomenes de la digestion 



chez les insectes. Mem. Acad. Roy. Belgique, t, xi, 



1'"'' partie. 



