PLATE VIII. 
DEVONIAN CRUSTACEA. 
Order—Merostomata, Dana. 
Sub- Order —EvuRYPTERIDA. 
Fic. 
1. Under side of Plerygotus anglicus, Agassiz, restored. 
2. Upper side of ditto. 
Fig. 2. 2. Larval eye-spots (ocell2). 
,, l. m. The metastoma or post-oral plate. 
1. op. The operculum (representing the coalesced pair of appendages be- 
longing to the vii" somite). 
Las Analvaperture: 
Bigs.) 2s be eyes: 
5 2. The chelate antenne. 
_ 3. The mandibles (endognaths, Huxley). 
rf 4. First maxille ( ditto Pa 
4 5. Second ditto ( ditto art) 
33 6. Maxillipeds (ectognaths, ee)? 
2,1, Position of small somewhat triangular plate united to the border 
of the penultimate joint, and overlapping the oval terminal 
palette. (See page 35.) 
4 vii. he head-shield, bearing the oce//i (7) and large compound eyes 
(1,1), and the operculum, or thoracic plate, which covers the two 
anterior thoracic somites (vii and ix) upon their ventral surfaces. 
% viii—xiv. Thoracic somites. 
»» xv—xix. Abdominal somites. 
» xx. The ‘telson’ or terminal segment. 
