NO. 3 



BURGESS SHALE FOSSILS WALCOTT 



23 



splciidois (see restorations). The jiresence of a rudinientary endop- 

 odite is suggested on some specimens by an elongate, triangular, 

 light-colored space on the proximal portion of the exopodites as shown 

 by figure 3, plate 20; these light areas may be the outline of a space 

 inside the broad arm of the exopodite, but they usually cross the axis 

 of the arm diagonally ; if they do represent the endopodite they were 

 exceedingly delicate and attached by a broad base beside the exopodite 

 in such a manner as to be held almost rigidly in place, and they are 

 always in the fossil state pressed against the proximal section of the 

 exopodite, and they have a silvery sheen so characteristic of the con- 

 tents of the inside of the limbs of all crustaceans of the Burgess shale 

 preserving the limbs. I do not think that they represent the endop- 

 odites, but they are the only suggestion of the latter thus far (jbserved 

 in connection with the abdominal limbs of IVaptia. 



thl ^ 



Fig. 7. — Wapha ficldciisis WalcoU. 



a, antennae; a.o., anal opening; c, carapace; c.f., caudal furca ; c, eye; ex. 

 exopodite; Ii.c, hepatic caeca; /, intestine; r. p.. rostral plate; sf, stomach; 

 fh. I., thoracic leg. 



(X3.) Diagrammatic side view of a section of tlie animal, ilkistrating tlie 

 appendages, digestive tract, etc. 



f mictions of appendages. — The functions of the antennules and 

 antennae were presumably sensory as in recent Malacostracans, as 

 they do not appear to have been modified for any other purpose, and 

 the proximal joint, as far as known, did not fimction as a manducatory 

 organ. 



The mandibles, maxillulae, and maxillae are unknown ; the five 

 pairs of thoracic limbs may have been used for crawling on the bottom, 

 but with short joints and spinous distal joint they could not have been 

 very effective; the exopodites of the eight i)airs of abdominal limbs 

 served as natatory organs and also as branchiae, the long delicate fila- 

 ments presenting an extended surface area to the water. 



Digestive organs. — What is known of the digestive system of 

 JVaptia indicates that it was somewhat similar to that of the living 



