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SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 1 37 



mere border line between two successive segments. However, the 

 dissection shows that we have to do with a true segment and that this 

 segment is a coxopodite. Despite the imperfect preservation of our 

 material, we saw that a group of muscles inserted in the insects near 

 the point where the trochantin articulates with the coxa, is inserted in 

 Anaspides on our coxopodite and not on the base of the coxopodite of 

 the other authors. 



The reduced segment is, on the other hand, not merely a trochantin, 

 a skeletal element which had never before been found in crustaceans 

 but which we had some reason to look for in these arthropods. If we 



Fig. I. — a, Basal part of the right maxilHped of Anaspides tasmauiac Thomson, 

 posterior view, setae omitted. From Hansen, 1925. b, Idem. From Snodgrass, 

 1952. c, Idem. Original; new interpretation. 



bp, basipodite ; ex, coxopodite ; ep, epipodite ; ex, exopod ; is, ischiopodite ; pi, 

 preischiopodite ; pe, precoxopodite. 



had to do only with a trochantin — the basipodite of Snodgrass and 

 ours — it would be one that should possess at least some features of a 

 coxa. But it actually resembles the insect trochanter by the extrinsic 

 musculature which is inserted on its proximal end, opposite to the 

 group of the levator and depressor muscles. In many insects the latter 

 group contains muscles arising from the notum, the longest extrinsic 

 muscles of the leg.^ Anaspides, however, had only rather short 

 depressor muscles. Since we raised the question of the trochantin of 

 crustaceans, let us point out that in the species of crustaceans where 

 it is found best differentiated, it still presents the appearance of a part 

 of the superior border of the coxa. This is to be recalled and examined 

 thoroughly when it comes to investigating the origin of the trochantin. 



8 See Lepismachilis (Barlet, 1946, fig. 2, TR-NT) ; but the said muscle does 

 not exist except in the anterior leg of the machilid. 



