﻿4D8 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 102 



border of the muscle arising close to the nerve cord; anteriorly they 

 do not join until close to the head. The spindle muscle, inserted in 

 the body wall dorsally just behind the anus, is free for a short distance 

 and then is fused to the gut wall as far as the coecum, beyond which 

 its attachment to the ascending spiral is by short muscular frenula. 

 The descending spiral from the esophagus is attached to the ascending 

 gut. Fixing muscles F^, F^, F^ are rather similar to those of zoster- 

 icolum; F^ sometimes consists of three strands arising from the same 

 point, or it starts as a single muscle and divides into two or three. 



A slight constriction of the gut just posterior to the attachment 

 of F' probably marks the end of the esophagus. In a large specimen 

 there are about 30 coils of the intestine (15 or 16 double coils). Along 

 the ascending gut is a conspicuous ciliated groove, terminating at 

 th€ coecum. 



The nephridia are free, very long, and attached to the body wall 

 slightly behind the anus. They may reach to the posterior end of 

 the body. 



The contractile vessel gives off dorsolaterally numerous anastomos- 

 ing branches, which form a network enclosing the esophagus, becoming 

 more complex posteriorly. Usually a midventral vessel leaves this 

 complex and runs far forward. For a short distance at the posterior 

 end of this net, numerous long, blind, often spirally coiled tubules 

 are given off from the dorsal vessel and also from some of the laterals. 

 Some of these branch near their base (pi. 29, fig. 3). 



Color in life: Ground color pale buffy, suffused with pale or warm 

 sepia, some examples decidedly dark at posterior end, collar pale 

 Hays maroon, madder brown, or liver brown (Ridgway's Color 

 Standards and Nomenclature, pis. 13 and 14); main stem of tentacles 

 the same; branclilets and tips pale yeUow, sometimes mottled with 

 madder. In alcohol, paler, the sphincter anterior to the zone of the 

 hooks becoming bluish or purplish. Some of the specimens from 

 Baja California are deeper, ruddy brown with rough sldn and reddish 

 brown tentacles. The very large specimen from Bodega Head, 

 Calif., M^as ochraceous-tawny on the trunk becoming paler on the 

 introvert. 



Young. — Up to about 18 mm. in length this species has no hooks or 

 spinelets on the introvert. In a considerable series there is a well- 

 expanded example 18 mm. long with four hooks well forward on the 

 introvert, placed symmetrically, two on each side of middorsal line. 

 A wide zone in front of and including anus is spotted with w^ell-spaced, 

 low, brownish glands of conspicuous size; behind this zone the spots 

 are very much smaller and closer together. In front of the anal zone 

 the glands are paler than the skin and transversely elongated. General 



