Crustacea — Trilohita. 



75' 



also as swimmerets, and in the female to support the eggs. In many GALLERY 

 respects the Trilobites are very near in structure to the modern Apus. -^^^^ ^^^^ 

 The great variability in the number of segments in Trilobites wallcases 

 had long ago led to the conclusion that they were phyllopods ; 13 & 14, 

 a knowledge of the simple biramose character of their limbs, as cases 

 well as the gradual diminution in the size of the segments, and 80-82. 

 their appendages, from the head to the pygidium (a feature which 



Fig. 123. — Olenellus Callavei, Lapw. Fia. 124. — Paradoxides Bavidis, Salter. 

 Lower Cambrian : Shropshire. M.Cambrian: St. Davids. 



Fig. 125 — Agnostus 

 princeps, Salter. 

 Cambrian : S. Wales. 



Fig. l26.—Olenus. 

 Upper Cambrian. 



Fig. 127. — Ogygia Buchii, Brong. 

 Ordovician : Llandeilo. 



