from the North Sea and adjacent parts. 179 



on the wliole tliafc of Po/j/«o^' Ja'7<a; indeed, the two forms 

 are closely united in many points. 



The proboscis has nine terminal papillje on either side — ' 

 the same number and of the same shape as in Lepidonotiis. 

 The four teeth alternate, are sliarply pointed, and have a plain 

 biting-edge supported by a ridge. 



Theel remarks that the feet and bristles of Bijlgia elegans 

 resemble those of Autinoe [Polynoe) sarsi and the dorsal 

 bristles those of Melcenis loveni, Malmgren. Tiie ventral 

 bristles are whip-like, being slender and drawn out into a 

 long fine tip. Tlie lower part of this bristle is decorated with 

 spines, which are shieU-shaped, point steeply upwards, and 

 are arranged in longitudinal rows. Above these, clothing 

 the tip of the bristle, is an investment of very fine hair-like 

 spines, and below tiiem, where the bristle is thickest, tiie 

 spines are smaller and more closely set together. As figured 

 by Theel, other ventral bristles are terminated in a slender 

 and slightly bent-over tip, but none of these were observed. 

 The transverse rows of spines of the dorsal bristles are 

 closely set together ; the tip is small and pointed, but not 

 acutely. 



The elytra are glabrous and the outer and posterior edge 

 has minute ciliform papilla3, as in Polynoe hadia. 



It will now be apparent that Thdel's diagnosis of the genus 

 Bylyia is wrong, in that it supposes the absence of anterior 

 peaks on the cephalic lobe and of a tentacle (median), and 

 the forward production of the anterior part of the head to 

 form the antennoe or lateral tentacles. 



When all points have been considered, it seems best to 

 refer Bylgia elegans to the genus Antinoe. The resemblances 

 between the present form and Antinoe spp. are numerous and 

 cover practically all the features of generic importance. 



Thdel himself remarktd that, in aspect, structure of the 

 feet, bristles, and number of scales, his Bylgia elegans closely 

 resembled Antinoe (Polytioe) sarsi. The numbers of seti- 

 gerous segments in the two forms are nearly alike ; the 

 structure of the head, disposition of the eyes and median 

 tentacle, the condition of the palps and proboscideal papillas 

 correspond. The resemblance between the set?e, especially 

 the ventral, is striking. While due consideration has been 

 given to the opinions of dififerent authors, e.g. Hansen (1882, 

 p. 1) and Harvey Gibson (1886, p. 342), regarding the value 

 of setal characters in specific or generic separation of forms 

 {cf. M'Intosh, 1874, p. 371), it is impossible from the struc- 

 ture of the setie alone to place Antinoe elegans in any known 



