146 [Assembly 



Rhynchobolus dibranchiatus Verrill. 



Olycera dibranchiata Ehlers. Op. cit., p. 670, pi. sxiv, figs. 1, 10-28. 1868. 



" " Grube. Op. cit., p. 64. 1869. 



Mhynchobolus dibratichiatus yKURihh. Op. cit., p. 596, pi. x, figs. 43, 44. 1874. 

 " " Webster. Op. cit., p. 245. 1879. 



Common ; low water to fifteen feet. 



GONIADA And and .1/". Edw. 

 Annales des Sciences Naturelles, vol. xxix, p. 266. 1833. 



GONIADA SOLITARIA 11. Sp. 

 PLATE (IV) YII, PIGS. 41, 42. PLATE (v) VIII, FIGS. 43, 44. 



Head as long as the first seven segments taken together, acutely 

 conical, with m'inute antennae. 



Eyes small, black, circular, lateral, posterior. 



Proboscis not seen in complete extension, covered with numerous 

 longitudinal series of stout hooks ; on the dorsal surface three rows 

 of hooks on either side of a naked median space ; on the ventral 

 surface four rows, two on either side of the median line ; one lateral 

 series ; ventral and lateral hooks smaller than the dorsal ; at the 

 base, on the ventral surface, numerous, quite small hooks scattered 

 about irregularly. 



The first twenty-five segments are nniramous ; the ramus has two 

 lips (fig. 41), anterior long and narrow ; posterior short and broad ; 

 dorsal and ventral cirri widely divergent, bluntly conical, dorsal a 

 little shorter than ventral. After the twenty-fifth foot a dorsal 

 ramus appears (fig. 42), composed at first of a broad, thick, squarish 

 plate, with a slight emargination near its upper margin, indicating 

 its future division into lips ; it contains from tliree to six straight 

 aciculse or setae, usually concealed, sometimes projecting slightly ; 

 the dorsal cirrus becomes smaller ; the other parts of the foot do not 

 change much ; further back the dorsal ramus is divided into two 

 bluntl}'^ rounded lobes (fig. 43). 



Anal cirri long, filiform. 



Setie of one kind only ; in two bundles, upper and lower ; upper 

 most numerous ; very long and slender ; the appendix nearly as 

 long as the stem (fig. 44). 



Body slightly convex above, flat below, anterior two-thirds of 

 uniform width, tapering a little along the posterior third. 



Color gray, slightly tinged with green. 



Length, 25°^'^' ; width, 1 . 3"". 



The only specimen taken was a female filled with eggs ; low 

 water, mud. 



Fam. THELETHUSIDJE. 



ARENICOLA Lamarck. 



Arenicola ? CRiSTATA Siimpson. 



Stimpson. Proc. Boston Soc. Nat. Hist., vol. v, p. 114. 

 QuATiiEFAGES. Histoire Naturelle des AnneUs, vol. iii, p. 673. 1865. 



