384 TORREY 



Family HALCAMPID^. 



" ActiniiiiEe with a small number of mesenteries, six, ten or twelve 

 pairs being all that are present ; longitudinal muscle pennons narrow 

 but strong ; no special sphincter muscle ; conchula present or absent ; 

 base usually rounded and vescicular." (McMurrich, 1893, P* ^4^0 



Genus Harenactis gen. nov. 

 Length great in proportion to the diameter of the column ; tentacles 

 twenty-four in number, in one series ; conchula absent ; cinclides in 

 twenty-four regular longitudinal rows ; base vesicular. Mesenteries 

 arranged hexamerously, in twelve pairs, all perfect above, two pairs 

 being directives, though there is but one siphonoglyph ; no acontia. 



HARENACTIS ATTENUATA sp. nov. 

 (PI. XXIV, figs. 4, 5; text-figs. 16, 17.) 



Locality. — San Pedro, Cal. 



This animal is found in the harbor of San Pedro, Cal., buried per- 

 pendicular to the surface in the fine sand of flats exposed at low tide. 

 Usually the tentacles rest upon the sand in full expansion, but oc- 

 casionally as much as half an inch of the column is exposed also. 

 When unduly stimulated it may withdraw several inches into its burrow 

 by shortening the body to less than half its length. 



The length of the column is remarkable in comparison with its di- 

 ameter. These dimensions at their maximum are approximately sixteen 

 inches and three quarters of an inch respectively. From its widest 

 point, in its oral third, the column tapers gradually to the base where 

 it abruptly expands. Just above this expansion it is extremely narrow 

 and weak, for which reason great care must be exercised to obtain a 

 perfect individual from the sand in which it lies buried. 



The base assumes various shapes, though never exceeding the column 

 in diameter. At times it becomes an almost spherical vesicle with 

 very thin walls traversed by lines which mark the basis of the mesen- 

 teries within (PI. XXIV, fig. 5) ; at others it may flatten into a thin 

 disk, in which condition I have found it adhering to a bit of shell. 



From the edge of the oral disk twenty-four tentacles arise. They 

 are in one series, although, as shown in PI. xxiv, fig. 4, twelve 

 curve upward and inward, alternating with the other twelve which ap- 

 pear to bend downward rather than upward. Each is not more than 

 three quarters of an inch in length, stout, with a bluntly pointed im- 

 perforate tip. Within the bases of the tentacles the oral disk is oval 



