4 BULLETIN: MUSEUM OF COMPAEATIVE ZOOLOGY. 



In 1900 the last quarter of the moon occurs on June 19 and July 18; 

 and as we do not yet know the limits of the lunar month in which the 

 worm swarms, we may look for it within three days of either of the 

 above dates along any of the Bahama or Florida reefs. It seems not 

 improbable that it swarms annually on one day of the year, and that 

 this day falls within three days of the moon's last quarter in the mouth 

 extending from June 15 to July 15. 



Description of the Adult Worm. — The genus Staurocephalus was 

 founded by Grube, 1855, who has given a s}Tiopsis of the genus and a 

 description of all of the then known species in the Jahres-Bericht der 

 Schles. Gesell. fur vaterl. Cultur., Ed. 56, pp. 109-115, 1878. Siuce 

 then two new species have been described by Mcintosh ('85, pp. 231- 

 235) ; and references to previously described species have been given 

 by Ehlers, Verrill, and Andrews. 



Generic Characters. — Annelida, Polycheeta, Family Xereidae ; body 

 vermiform, segments distinct. The head-lobes give rise to one or two 

 pairs of jointed tentacles. When two pairs of tentacles are present, one 

 pair arises from the side, and the other from the ventral surface. Eyes 

 are sometimes present. The two first segments are without parapodia. 

 The parapodia possess dorsal and ventral cirri. The dorsal cirrus is 

 often unjointed, but sometimes possesses a short terminal segment. 

 The ventral cirrus is shorter than the dorsal and is unsegmented. The 

 posterior segment has two long dorsal and two short ventral cirri. 

 The upper jaw consists of two simple, connected pieces. The lower 

 jaw consists of two rod-like pieees which approach each other near the 

 middle but diverge both in front and behind. (See Figures 20, 22, 26, 

 27, Plate 3.) 



Specific Characters ; Adult Worm. — The worm is about 120-150 mm. 

 in length ; and may be even longer, for the posterior segment has not 

 been observed. The segments are distinct, and there are about 17 

 raetameres per centimetre of the worm's length. The worm is about 

 4 mm. broad. The ventral surface is quite flat and a deep groove runs 

 down its centre. The dorsal surface is arched, and the dorso-ventral 

 diameter is about 3 mm. There are no eyes, but the hypoderinis cells 

 of the front end of the praestomium bear a dark rosin-colored pigment, 

 the presence of which may indicate a general sensibility to light. There 

 are no lateral tentacles upon the head, but the ventral praestomium 

 gives rise to two quite stiff tentacular cirri (see Figures 1-3, 9-12). 

 Tliese cirri consist each of but a single joint. An axial nerve runs 

 down the centre of each tentacle, and this nerve is surrounded by 



