SECT, xv CLASSIFICATION OF CRUSTACEA 275 



Anteriorly, we find that the shell has been cut off, 

 an arrangement which the next form, Ceratiocaris, 

 fully explains. 



Ceratiocaris differs somewhat from Hymenocaris, 

 but shows even closer resemblance to the Apodidae. 

 We have the caudal plate and two anal cirri, which 

 are clearly, as in Apus, the ventral pair. If the fossil 

 were well enough preserved, we might perhaps find, 



FIG. 64. Ceratiocaris papilio Salter. Upper Silurian. Showing the rostrum, the 

 first pair of antennae, and the mandibles (from Zittel). 



as in Apus, the rudiments of the dorsal pair. Im- 

 pressions of the mandibles are clearly visible, and 

 bear the closest possible resemblance to those of 

 Apus. Traces of branchial limbs have been found 

 on the abdominal segments of Ceratiocaris Stygia. 

 Anteriorly, however, we find the same piece of the 

 shield cut out as in Hymenocaris, with remains of a 

 rostrum and anterior antennae. The antennae bear a 

 close resemblance to those of Apus (see Fig. /A, p. 34) 



T 2 



