CONTENTS 



1. Dalmat, Herbert T. The black flies (Diptera, Simuliidae) of 



Guatemala and their role as vectors of onchocerciasis. 425 pp., 

 44 pis., 21 figs., 14 maps. Apr. 5, 1955. (Publ. 4173.) 



2. Bartsch, Paul. The pyramidellid mollusks of the Pliocene de- 



posits of North St. Petersburg, Florida. 102 pp., 18 pis. May 5, 

 1955. (Publ. 4186.) 



(v) 



