32 



NoiHh, American Palaeozoic Crustacea. 



The under side of Ptertgotus anglicus, Agassiz, restored. 



1. Eyes. 



2. Chelate antennae. 



.3. Mandibles [Endognaths, Huxley]. 



4. First maxillae [Endognaths, Huxley]. 



.'). Second maxilla; [Endognaths, Huxley]. 



6. Maxillipeds [Ectognatbs, Huxley]. 



i, i, Position of small, somewhat triangular, plate united to the border of the 



penultimate joint, and overlapping the oval terminal palette. 

 vii, The head-shield, bearing the ocelli [I] and large compound eyes [II], and the 



operculum, or thoracic plate, which covers the two anterior thoracic somite? 



Iviii and ix] upon their ventral surfaces. 

 viii-xiti, Thoracic somites. 

 xv-xiz, Abdominal somites. 

 XX, " Telson" or terminal segment, 

 m, Metastoma or post-oral plate. 

 op, Operculum [representing the coalesced pair of appendages belonging to the 



viith somite]. 



Note. — The figure and nomenclature are copied from Dr. Henry Woodward's 

 excellent Monograph of the British Fossil Crustacea belonging to the order 

 Merostomata, plate viii. 



