NO. 4 HARTMAN : SPIONIDAE FROM CALIFORNIA 295 



The prostomium is greatly prolonged anteriorly, pointed, widest 

 where it meets the peristomium at the anterior margin. There is a trans- 

 verse groove just anterior to the eyes (pi. 45, fig. 1 ). A high nuchal ridge 

 is continued posteriorly a short distance to the third setiger. The palpal 

 bases are at the sides of the ocular ridge. The peristomium is a long, 

 achaetous ring at the sides of the prostomium. The first setigerous segment 

 has only neurosetae; the second is the first branchial segment. Hooded 

 hooks are distally tridentate (pi. 45, figs. 4, 5). 



During the early part of May, 1938, eggs and spermatozoa were re- 

 moved by breaking open the body wall of seemingly mature individuals 

 of Nerinides acuta. The egg is elongate ellipsoid, measures approximately 

 0.21 by 0.129 millimeters, and is greatly depressed when seen from the 

 side. It is covered by a thick membrane, its surface highly sculptured with 

 larger and smaller depressions (pi. 45, figs. 7, 8). It is semitranslucent ; a 

 clear vesicle may be distinguished near its center, and smaller clear spots 

 at the narrowed ends. The spermatozoa are highly motile, minute, oval 

 bodies with long tail (pi. 45, fig. 6) . 



Attempts to inseminate eggs artificially in May resulted in a shrinking 

 away of the cytoplasm from the egg membrane. Normal development was 

 not obtained. Numerous planktonic young individuals of what is believed 

 to be this species were collected during May. Also, early sedentary stages 

 were found in great numbers in sandy beaches at Spindrift, near La Jolla, 

 on May 4, 1938. A comparison of various stages from the plankton and 

 from sandy beaches suggested a probable picture of its development. The 

 youngest sedentary stages observed had 23 segments and measured 1.6 mm 

 long in life. General appearance was much like that of the adult, with 

 greatly prolonged prostomium. The palpi, however, were short, extend- 

 ing posteriorly only to about the fourth or fifth setiger. Branchiae were 

 present from the second segment. The gastric area between segments 8 

 and 15 was dark. Hooded hooks were present from the thirteenth setiger. 

 The pygidium was nearly hemispherical, provided with a ciliated telo- 

 troch. 



A similar, earlier stage was taken in plankton late in May, and kept 

 in culture for about a week. The same greenish color with a deep black 

 streak marking the alimentary tract was visible through the body wall, 

 just as in early sedentary stages ; palpi were short. The prostomium and 

 anterior end were prolonged, pointed, with 4 dark eyespots (pi. 45, figs. 2, 

 3). The pygidium was collarlike, with dorsal groove and well-developed 

 telotroch. 



