1910.] NATURAL SCIENCES OF PHILADELPHIA. 329' 



into the bases of the lateral tentacles, but a well-marked articulation 

 cuts off the latter as distinct ceratophoric segments. 



One example has the proboscis protruded. It is large and evidently 

 powerful, 5 mm. long, 2.7 mm. wide, cylindroid, little depressed dis- 

 tally, smooth. There are nine dorsal and nine ventral prominent 

 apertural papilke and behind each series a small rounded median 

 tubercle. Jaws pale brown, with large blunt fangs, the lower biting 

 to the right; lateral cutting plates thin, low, rather extended bu1 

 weak and directed chiefly laterally. 



Stations 4,310. off Point Loma, vicinity of San Diego, 71-75 fathoms, 

 green mud and fine sand; 4,414, northwest of Santa Catalina Island, 

 156-162 fathoms, fine gray sand andjmud; 4,420, northeast of San 

 Nicolas Island, 33 fathoms, fine gray sand; 4,453, off Point Pinos 

 Light, Monterey Bay, 56-62 fathoms, green mud, "on Luidia;" 4,457,. 

 same locality, 40-46 fathoms, dark green mud, "on Luidia." 



Halosydna insignis Baird. 



Halosydna insignis Baird, Journ. Linn. Soc London, VIII (Zool.), 1805, 



p. 188. 

 Polynoe brevisetosa (Kinberg), Johnson, Proc. Cal. Acad. Sci., Ser 3., Zoology, 



I (1897), p. 167. Figs. 24, 31, 40 and 40. 



This very remarkable species is well represented in the collection by 

 both the commensal and the free-living phases. Were it not that 

 Johnson's familiarity with the species in its native surroundings enabled 

 him to demonstrate their identity workers on preserved material 

 alone would almost certainly have separated them as distinct species, 

 though close inspection shows that they agree in their strictly technical 

 characters. 



Though there are no accompanying notes specifying their hosts 

 or associates it is evident that most of the examples were commensals, 

 they having the elongated form and other characteristics of this phase. 

 The specimens measure from 15 to 45 mm. long, the smallest, while 

 intermediate in proportions, approximating the short stout form of 

 the free-living rather than the slender, elongated form of the commensal 

 phase. As is the case with the former the ely t ra are strongly imbricat e< 1 

 and cover the middle of the back nearly or quite completely. Both 

 phases exhibit color variations through various shades of gray and 

 brown or dusk}- and the elytra, while usually mottled, may be quite 

 plain and uniformly colored. The pigment may be arranged in dis- 

 tinct spots or assume a reticular patternfaround paler areas as in 

 H. calif ornica Johnson. Most constant is a white spot over the 

 pedicel of attachment and a black or deep brown spot mediad of or 

 behind it. Some specimens with elytra otherwise completely pig- 



