A STUDY OF THE LIFE-HISTORY AXD HABITS OF 



CH.ETOPTERUS VARIOPEDATUS, REXIER 



ET CLAPAREDE. 



HOWARD EDWIN ENDERS. 

 With Three Plates. 



Introductiox. 



While I was at Beaufort, ^orth Carolina, during the season of 

 1003, I became interested in the peculiar modifications that adapt 

 Chsetopterus to its sedentary mode of life. At the suggestion of Dr. 

 E. A. Andrews I undertook to study its embryology and anatomy the 

 following season, but was unable to rear the larvse beyond the stages 

 which E. B. Wilson has described. Toward the end of the season 

 of 1905 I was successful in rearing lan^se from eggs to such a stage 

 that it was possible to know the younger larvse collected in the tow- 

 ings. I was fortunate enough to find a sufiicient number of Chsetop- 

 terus larvse in the towings to observe the important stages in the life- 

 history and to rear the younger ones in the aquaria. In a brief 

 time they grew to stages that correspond with the young worms on the 

 sand flats. I have now two worms living in the laboratory of the 

 Johns Hopkins University that grew from larvae taken in the tow- 

 net more than ten months ago. 



The muscular movements of the older larvae were so strong and 

 rapid that it was impossible to make projection drawings of them, 

 i^arcotization Avas unsatisfactory, so they were drawn by the aid of 

 measurements made with a micrometer eye-piece. 



I have sectioned some of the larvse, but the number of specimens 

 is insufficient for a complete study. T hope to present the results 

 of a histological study of Ch?etoptcrus in a later paper. 



Thr .TotiiXAL OF Morphology. — Vol. XX. No. :?. 



