24 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 85 



A pus. The elongate globular stomach (st), with the small digestive 

 or hepatic glands (d. gl.), long simple intestine (i) terminating on the 

 last segment at the anus {an) all suggest corresponding organs in 

 Apus, and it is highly probable that the mouth was ventral and com- 

 municated with the stomach by a gullet extending upward and for- 

 ward. The shell gland (sh. gl.) or renal organ is distinctly marked 

 in several specimens and, as far as comparison is possible, is not 

 unlike that of Apus. 



Observations. — Waptia was a pelagic, free and active swimming 

 animal using its abdominal limbs and the broad terminal rami for 

 propulsion. The fact that it is found in association with algae and 

 sponges is explained by the conclusion that the sessile forms of life 

 were detached and drifted into the Burgess pool and deposited along 

 with the pelagic forms that dropped to the bottom of the sea.' 



The carapace of Waptia is much like that of Hymenocaris except 

 that it is not separated into two equal parts by a median longitudinal 

 hinge line, and there is no evidence of the presence of an adductor 

 muscle scar on each side as in Hymenocaris. 



DIAGRAMMATIC RESTORATION OF VENTRAL VIEW OF THE 



BODY AND APPENDAGES, WITH OUTLINE OF 



DIGESTIVE ORGANS 



Most of the data on which the restoration is based is shown by 

 the specimens illustrated on plates i8, 19 and 20. The form and 

 position of the cephalic appendages are unknown with the exception 

 of the antennae and possibly antennules ; the proximal joints of the 

 thoracic and abdominal limbs are outlined on the specimens though 

 their form is not preserved, but otherwise the limbs are fairly well 

 known. The body cavity is outlined by figure 3, plate 18, but it is 

 not included in this diagrammatic figure. The shell glands {sh. gl.), 

 stomach, intestine, and hepatic caeca are outlined, as they represent 

 what is known of the digestive organs. 



Plesiotypes.~U. S. N. M., Nos. 83948a-e. 



WAPTIA CIRCULARIS, new species 

 Plate 21, fig. 3 



A single specimen with a short, rounded carapace was labeled W. circularis by 

 Doctor Walcott. As far as the rather poor preservation permits a determination 

 it would seem that otherwise it is similar to \V. fieldensis. 



Holotype.—\J. S. N. M., No. 83449. 



^ Smithsonian Misc. Coll., vol. 67, no. 5, pp. 219, 220, 1919. Idem, no. 6, p. 265, 

 under Habitat. 



