MAYER: STAUROCEPHALUS GREGARIOUS. 3 



worms continued to increase in numbers until the time of the rising of 

 the sun, and then, as the light of the early morning fell upon them, a 

 series of contractions came over the sexually ripe segments of each 

 w'oi'ra and the eggs or sperm were thus discharged into the water (see 

 Figure 2, Plate l). This contraction is often so sudden and so violent 

 that the ripe segments are torn asunder, at short intervals, by the 

 breaking of the cuticula, forming large rents through which the genital 

 products escape. The 25-30 anterior segments of the worm contain no 

 sexual elements, and take no part in the contraction, so that they re- 

 main uninjured, and always retain their natural shape and appearance. 



After the discharge of the sexual products the worms c<jntinue to 

 swim near the surface for a considerable time, dragging their torn and 

 contracted sexual segments after them. Sometimes, indeed, the con- 

 traction causes the sexual segments to break away from the anterior 

 portion of the worm, and they swim about, apparently suffering no in- 

 convenience, although without a head. After the discharge of the eggs 

 or sperm the sexual segments become very brittle, and a touch of the 

 hand is often sufficient to cause them to break suddenly into small frag- 

 ments. It seems not improbable that the torn and contracted sexual 

 segments may eventually slougli off from the 25-30 anterior ones, and 

 that thus the life of tlie individual may be saved to perpetuate the 

 species. This, however, is mere conjecture upon my part, for in 1898 

 all of the worms which were confined in aquaria died during the course 

 of the day without having thrown off their dishevelled posterior seg- 

 ments ; and in 1899, when four of the worms were placed in a large 

 aquarium the bottom of wliich was covered with sand and stones, tliree 

 of the worms ci'awled under the stones, but all died within two days 

 without having thrown off their contracted sexual segments. 



At G.30 A. M. the worms began to sink down upon the sandy bottom 

 of the ocean, and by nine o'clock in the morning none of then) were to 

 be seen. Large numbers of fish devour the worms during the time 

 of swarming. 



There is little or no sexual color diffei-euce in the worms, both males 

 and females being dull brick-red. The females, however, are sometimes 

 of a duller and more yellowish tint than the males. The sperm is yel- 

 low-bufi' or slightly pink in color, while the eggs are yellow or greenish 

 yellow. The genital products escape in such quantity that the sea is 

 rendered milky over wide areas, and long after the worms have disap- 

 peared the eggs remain floating near the surface in visible windrows of 

 yellowish color. 



