289 



warts, but we cannot inakc out by the aid of' the warts whcther 

 the k)bes at the back of'tlie XTIItli segment whieh are sepavated by 

 an ineision, are to bc considered as remnants of the ventral part of 

 a Xiytli segment, because the reguhir succession of the legless 

 rings on the ventral side has been interrupted by the back feet." 



Sharp (1901) however says on II p. 323: "The caterpillar is 

 composed of a head and thirteen divisions or segments of the 

 body, the first three of the latter are called thoracic, the other 

 ten abdominal segments, in most caterpillars the terminal two or 

 three abdominal segments are more or less run together, and the 

 ninth may be very small, so that the true number is indistinct." 

 Thus he leaves this highly important question of the number 

 of primary segments unsolved. 



J. Tn. OuDEMANS thinks (1897—1900, p. 63) that the number 

 of the abdominal segments is ten and that those who take it to 

 be eleven are wrong. 



Fracker (1915) says of a full-grown Hepialus (p. 29): "We 

 may consequently conclude that the setae give no evidence for 

 considering the anal segment to be composed of more than one 

 metamere either in its dorsal or ventral portions. Those who 

 have asserted that the setae show that this segment consists of 

 more than one somite, have not studied the data carefully on which 

 their opinions were based." 



Against this we may say that Fracker does not speak of the 

 arrangement on the newly hatched larva and that as early as 1886 

 Muller observed that the first instar only showed this last 

 segment distinctly, whilst at the same time we may contend that 

 features, holding good for a certain form, may prove to be falla- 

 cious for another. 



Handlirsch (1903) on the basis of morphological, embryological 

 and especially palaeontological investigations, came to the con- 

 clusion that insects, except the Collembola, possess eleven abdominal 

 segments and a telson. In all the primitive insects this llth segment 

 ends in two cerci. 



Neither do writers agree on the primary number of abdominal 



