24 PEOCEEDINGS OF THE NATIONAL MUSEUM vol. 78 



Holmgren, N. 1916. Zur vergleichenden Anatomie des Gehirns von Polychae- 



ten, Onychophoren, Xiphosuren, Arachniden, Crustaceen, Myriapoden, und 



Insecteu. K. Svenska Vetensk. Handl., vol. 56, p. 1. 

 Kennel, J. 1885. Entwicklungsgeschichte von Peripatus edwardsi und Peri- 



patus torquatus n. sp. Arb. Zool. Zootom. Inst. Wurzburg, vol. 7. p. 95. 

 Lankester, E. R. 1900. A treatise on Zoology. Part 2. The Porifera and 



Coelenterata. Chapter 2, The Enterocoela and the Coelomocoela. London. 



A. and C. Black. 

 Walcott, C. D. 1911. Cambrian Geology and Palaeontology, II, No. 5. Middle 



Cambrian Annelids, Smiths. Misc. Coll., vol. 57, p. 109. 

 Walton, L. B. 1927. The Polychaet Ancestry of the Insects. Amer. Nat., vol. 



61, p. 226. 



DESCRIPTION OF PLATE 



Figure 1. Aysheaia pedunculata Walcott, specimen c. (X IV2). 



2. Aysheaia pedunculata Walcott, specimen b. (X l^/a). 



3. Opabinia regalis Walcott, supposed female (X IVz). 



4. Opabinia, regalis Walcott, supposed male (X li/^). 



Figures 1 and 4 are from retouched photographs left unpublished by the 

 late Dr. C. D. Walcott ; Figures 2 and 3 from unretouched photographs prepared 

 under the direction of Dr. C. E. Resser. 



U S, GOVERNMENT PRINTING OFFICE: 1990 



