212 Mr. R. MacLachlan's Monograph of 



" The legs are short ; the coxaB thick and cone-shaped ; 

 the femora cylindrical, with a narrow but distinct horny 

 ring at the base ; the tarsi are cylindrical, and between 

 them and the tibiee is, posteriorly, a small peg-like 

 appendage surrounding the hinder part of the tarsus at 

 its base ; one might look upon this as a trochanter, but 

 then it would be necessary to consider the coxse as con- 

 tinuations of the thorax (as, indeed, such are found in 

 the larvae of Phryganidcn) , and then the coxfe would be 

 what have been termed thighs, but in that case we miss 

 the separation of the tarsus and foot ; the foot is very 

 short, conical, ending in a small simple hook, only well 

 seen on the hinder pair. The thoracic segments, how- 

 ever, leaving the legs out of the question, are of equal 

 thickness with the seven following abdominal segments, 

 and the meso- and meta-thorax agree in structure with 

 them, only they do not bear any spiracles. The first to 

 the seventh abdominal segments bear, each in the middle 

 above, a broad triangular spot rolled up behind, within 

 which the skin looks harder and horny ; the rolled up 

 portion bears on each side two bristles ; on each side of 

 this spot is a smaller horny plate, the hinder end of which 

 becomes gradually more warty, and bears one bristle ; 

 posteriorly the middle plates gradually disappear ; in 

 place of the harder plate-like skin, there stand small 

 wart-like protuberances, and on those, as previously 

 mentioned, are placed the four bristles ; the skin is of 

 a darker colour round the spots. On closer examina- 

 tion, one observes that each end of the middle plate, 

 standing above in the middle, consists of four smaller 

 parts, divided by a cruciate membranous furrow. On 

 the sides of the second and third thoracic segments are 

 two dark horny wart-spots, one beneath the other, and 

 on the sides of the first to the eighth abdominal seg- 

 ments are three such small plates in a triangle, the fore- 

 most of which bears the spiracle. On the underside of the 

 said segments are nipple-like abdominal feet, increasing 

 in size posteriorly. As peculiar distinctions, the eighth 

 and ninth segments bear on the upper side two large 

 cylindrical warts with a long-jointed bristle, and the 

 tenth a median upper one. Out of the tenth segment a 

 four-jointed holding-fork can be protruded, the spikes of 

 which are blunt and cylindrical, two standing out side- 

 ways, and two straight behind. Internally numerous 

 muscles approach this fork, the border of which is trans- 



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