286 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 10 



2. Tube dextral Dexiospira spirillum 



3. Opercular stalk cylindrical, operculum funnellike 



Serpula vermicularis 



3. Opercular stalk with knoblike protuberances, operculum funnel- 

 like Crucigera zygophora 



Serpula vermicularis Linneaus 



Fauvel, 1927, pp. 351-352, fig. 120. 



This cosmopolitan species inhabits rocky places at Tomales Point and 

 Dillon Beach. Tubes are hard, white, cylindrical, but somewhat coiled 

 near the base. The tentacular crown and operculum are often brilliantly 

 colored red and white. Length is about 50 to 70 mm. 



Crucigera zygophora (Johnson) 



Serpula zygophora Johnson, 1901, pp. 433-434, pi. 19, figs. 205-208. 



At Tomales Point and Dillon Beach this occurs in rocky habitats. 

 Tubes are thick, white. Length is 40 to 60 mm. 



Subfamily Spirorbinae 



These serpulids are conveniently separated from the subfamily Serpu- 

 linae in the following characters : they are notably smaller, the tube is 

 typically closely coiled, the body is asymmetrical and similarly coiled, the 

 thorax consists of less than 5 setigerous segments, and the calcareous 

 operculum has a smooth stalk, its distal, expanded portion used either 

 simply for closing the tube or also as a brood pouch. Hermaphroditism 

 is the rule. All species in this category have sometimes been considered 

 as Spirorbis; but, since the group is a large, unwieldy one, it is preferable 

 to recognize finer divisions (see Caullery and Mesnil, 1897, and others). 



Two species are here recognized from the Dillon Beach areas, but 

 others are to be found. 



Key to Species 



Tube sinistral (that is, the aperture is on the left side when the tube 

 is placed with opening below) ; thorax consists of 3 setigerous 

 segments; collar setae distally crenulate . Laeospira borealis 



Tube dextral (aperture is on the right side when the tube is placed 

 with opening below) ; thorax consists of 3 setigerous segments; 

 collar setae distally crenulate .... Dexiospira spirillum 



