EURYTHOE COMPLANATA. 29 



from Patagonia northward to California. It seems to be extremely abundant 

 on the coral reefs of the Pacific Islands. E. complanata was described originally 

 from the West Indies, E. alcyonia from the Red Sea, and E. pacifica from the 

 Society Islands (Eimeo); but the forms identified by different writers under 

 these three names overlap extensively in their ranges and at the same time 

 present no distinctive morphological characters that have been thus far pointed 

 out. Slight differences in the setae occur in specimens from many different 

 localities; and it is quite likely that after the minute study of abundant material 

 it will be possible to limit various local varieties ; but such discrimination seems 

 impossible in the present state of our knowledge. I do not find that the sup- 

 posedly characteristic serrations of the furcate setae of dorsal and ventral 

 fasciae in E. pacifica are present even in most specimens from the general type- 

 locality. E. corallina Kinberg I regard as having been based upon young speci- 

 mens of this species, the number of buccal segments having been found to vary 

 with age. 



Specimens from all the localities mentioned agree in general form and pro- 

 portions, the body having a flattened form of subrectangular cross-section about 

 twice as wide as high. The oval prostomium has four eyes; the tentacles are 

 short, with the median shorter than the lateral and scarcely as high as the adja- 

 cent caruncle. The caruncle does not extend beyond the fourth segment. 

 There are three or four buccal segments. Both the dorsal and the ventral cirri 

 are shorter than the setae and are jointed. Notopodial setae include besides 

 the prevalent straight serrate type, a very slender furcate type, the branches 

 of which are fine. The neuropodial setae are of a much stouter furcate type in 

 which the branches are stout. In both furcate types serrations may or may not 

 be present. While the setae vary obviously in form, it does not seem possible 

 at present to define varieties or subspecies on this basis. (See Plate 14, fig. 3-9). 



The specimens from the Galapagos conform in the features above mentioned. 

 The midventral line is dark as in many specimens from the Paumotus, etc.; 

 but, in addition, there is a slight darkening in a narrow band adjacent to the 

 parapodia both above and below. The dorsal surface is more strongly sulcate 

 and roughened than usual. The smallest specimen is 53 mm. long and 6 mm. 

 wide, exclusive of the setae. It is composed of seventy somites. The inter- 

 mediate specimen is nearly 100 mm. long, has a maximum width of 11 mm. 

 and embraces one hundred and two somites. The third specimen is much 

 larger and greatly exceeds other specimens of the species of which I find measure- 

 ments recorded, and presents a correspondingly large number of somites. It is 



