178 Mr. W. Small on Annelida Folyclcata 



eJegans, because of its small number of segments [l^'^), lack of 

 setfe, and bad preservation — shows tlie violet-brown colour ot 

 the dorsum, the deep violet-over-grey of the proboscis, and 

 the violet palps mentioned in the original description. The 

 majority of the examples are brown-coloured on the dorsum, 

 resembling Theel's Polynoe hadia (1879, p. 18). Tiie ventral 

 sui-face and the feet are a uniform grey-white and the bristles 

 are golden yellow. 



Tiieel regarded the genus Bylgia as diverging from other 

 polynoids after the manner of Kinberg's family I])hionea, 

 because of the absence of a median tentacle, but as being- 

 removed from the genus Tphione because of important anato- 

 mical differences. Examination of the present specimens 

 would seem to show tiiat Theel's Bylgia is very closely 

 related to the other polynoids and that his diagnosis of the 

 genus is a mistaken one. 



The head is as broad as it is long, the greatest breadth 

 being in front of the transverse middle line. It is divided by 

 a median incision, which narrows posteriorly and passes 

 backwards a little beyond the level of the anterior pair of 

 eyes. There are thus the usual two lateral eminences, and 

 these are pear-shaped and produced anteriorly into two very 

 distinct peaks which are not produced forward into the an- 

 tennae. These peaks were not observed by Th^el. Levinsen 

 (1883, pp. 38, 195) has apparently not examined the annelid ; 

 at any rate, he mentions the absence of projecting peaks as a 

 diagnostic characteristic of ByJgia elegans. All the present 

 examples having heads, five in number, show the condition 

 described above. The anterior eyes are the larger and are 

 well removed from the front of the head and placed near its 

 lateral border on the highest parts of the eminences. The 

 posterior eyes are more closely set together than the anterior 

 and are situated near the nuchal border of the head. Tlie 

 space between the peaks is tilled with the massive rounded 

 base of the median tentacle. This base is present in every 

 specimen, but no example of the tentacle. Having their 

 origin below the peaks are the two lateral tentacles. These 

 have a strong basal portion, are conical in shape, and uni- 

 formly tapered to a point. Theel avers that their bases are 

 partly united to form one, but in the present examples the 

 base of the median tentacle is interposed. The palps are 

 remarkably large — larger than Tlicel's drawing indicates — 

 and are supplied with minute papillce which escaped Theel's 

 observation. They have no filiform prolongation of the tip. 

 The tentacular cirri have all been lost. The head resembles 



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