PLATE 10. 

 From photographs made by C. E. Beecher. 



Fig. i. Isotelusjatus Raymond. Ventral surface of the specimen in the Victoria 

 Memorial Museum at Ottawa, Canada. Note the large, club-shaped coxopodites and the 

 more slender endopodites. The first large coxopodite back of the hypostoma belongs to 

 the last pair of cephalic appendages. The coxopodite of the appendage in front of it is seen 

 turning in beneath the tip of the hypostoma. x 2. 



Fig. 2. Isotelus maximus Locke. The ventral side of the specimen described by Mickle- 

 borough and now in the U. S. National Museum. The tips of the hypostoma may be seen 

 at the front, and the first two pairs of coxopodites behind them belong to the last two pairs 

 of appendages of the cephalon. Note how much stronger the coxopodites are than the en- 

 dopodites. The appendages of the pygidium show but poorly, x 1.45. 



