﻿SIPUNCULID WORMS OF CALIFORNIA — ^FISHER 433 



backward in varying degrees, sometimes assuming the stature of short, 

 sharp spines. However, there is much variation. In Httle specimens 

 and a few adults the enlarged spines remain symmetrically conical. 

 The dorsal light-rcddish-brown pigment of the spine area is continued 

 forward, sometimes subdivided into transverse patches of color, 

 becoming darker in the narrow zone of the hooks. The platelets of 

 the smaller papillae are numerous, close to one another, and decrease 

 in size from the central clear pore zone to the periphery, where they 

 are little more than granules. In the outer zone there are no larger 

 platelets among the small ones, as in Ph. agassizii. In the larger 

 specialized papillae, or tubercles, of the introvert the platelets are 

 relatively larger, thicker, more crowded and heavily pigmented. 

 Immediately around the pore zone the platelets arc usually a little 

 smaller than those over the remainder of the tubercle. On the anterior 

 half of the introvert the papillae are elliptical in outline, become 

 gradually very small (0.07 to 0.1 mm. long diameter) and the platelets 

 are reduced to granules, retreating more and more to the central 

 portion immediately surrounding the pore. 



The hooks form 16 to 21 dark-brown rings, the posterior rings 

 being sometimes incomplete from loss of hooks. The hooks are 

 characteristic in having the terminal portion sharply bent, in com- 

 bination with an unusually large, clear, triangular space, which is 

 separated from the median clear streak (not merged with it as in 

 puntarenae and nigrescens). Note the dilation of the clear streak. 

 The so-called tooth on the concave border of the hook may be well 

 developed or absent. 



In three adults the tentacle counts are 12, 13, 15. Tentacles more 

 or less pigmented with dark ohve. The nuchal organ is large and 

 similar to that of agassizii. The smooth zone between circumoral 

 collar or ridge and the collar just in front of the hook area is divided 

 into an uncolored anterior half and a brown half. 



The internal anatomy differs from that of agassizii only in minor 

 details. The longitudinal muscle bands anastomose more freely in 

 some individuals than in others. There are 18 to 20 bands at the 

 origin of ventral retractors. The latter have a broad base arising 

 from the muscle bundles 3-6, varying to 2-5, the dorsal retractors, 

 about the same distance in front as agassizii, arise on left from 4-6 

 or 5-7 and on right from 6-7 or 4-6. The fixing muscle arises on the 

 left of the nerve cord at the same place as in agassizii and, forking, 

 is attached to the esophagus and to the intestine a short distance 

 posterior to the coecum. The spindle muscle is strong and is very 

 similar to that of agassizii. 



There is a well-developed subspherical coecum. The intestinal 

 spiral is of moderate length with about 16 to 18 single whorls. 



