EXPLANATION OF PLATES • 213 



Sphaerocoryphe major sp. nov. 

 p. 67 



Fig. 



13 Dorsal view of cranidium partly restored at the genal angles. 



Natural size • 

 From a pebble of group 5 



14 Copy of a mature specimen of Sphaerocoryphe 



robustus Walcott, in the state collection. Natural size 



Pterygometopus eboraceus Clarke 

 p. 69 



15 A cranidium. x 2 



Pebble of group 7 



Lepidocoleus jamesi Hall & Whitfield sp. 

 p. 87 



16 A plate retaining the surface sculpture, x 10 



17 The latter enlarged, x 25 



18 Another plate where one of the two systems of etriations is 



more strongly developed, x 10 



19 Surface sculpture, x 25, showing the minute nodes appear- 



ing where the cross-striations intersect the transverse 

 striae. The nodes are drawn a little too prominent. 

 Pebbles of group 5 



Problematic crustacean 



20, 21 Two views of the periderm of an organism which on 

 account of the substance, general form and porosity of 

 the shell proibably belonged to the crustaceans. The 

 symmetry of form ehown in the outline of the shell and 

 the position of the nodes would combat a reference of 

 the form to the Ostracoda, which, at first glance, are 

 suggested by the general form. It is possible that 

 the specimens may be the head shields of a species be- 

 longing to the Merostomata. The description of the 

 form is deferred till a fuller series of specimens has been 

 obtained, x 10 



22, 23 Two views of another, partly decorticated specimen, which 

 show that the underside of the shell possesses depres- 

 sions correspondimg to the nodes, x 10 



24, 25 Two views of a very small shell xirobably belonging to this 

 organism, showing two faint symmetrically arranged 

 nodes, x 10 

 Pebbles of group 7 



