AMPHARBTID^J. 



63 



the nephrostome opening into a thoracic chamber and the nephridiopore to the exterior a 

 little behind the first bristle-tuft. This pair is purely excretory. The second pair are 

 shorter, of a flask-shape, and have the typical structure (Fig. 1.45). These give exit to 

 the sexual elements (Fauvel). In the majority of the group the opening of the segmental 

 organs is on the dorsum behind the branchiae. The nerve-cords are perhaps less free in 

 this group than in the Amphictenidae. 



Sars (1835) first introduced this group to science by the description of "Amphitrite 

 Gunneri " and Sabella ? octocirrata, though he placed the species under the Terebellids. 



This family was instituted by Malmgren (1865, his Ampharetea), for the northern 

 species, which he placed in two main groups according to the number of the segments and 

 the condition of the frontal lobe. Thus, in the first group having from twenty to forty 



GV R' 



Fig. 144. Fig. 145. . 



Fig. 144.— Nephridia and ventral glands of Ampharete Grubei. na., anterior nephridia ; np., posterior 

 nephridia ; gl.v., ventral glands ; pv ., ciliated funnel. (After Fauvel.) 

 Fig. 145.— Structure of a posterior nephridium. Be., nephridiopore ; pv., ciliated funnel; vv., blood-vessel. 



(After Fauvel.) 



segments and a conspicuous frontal lobe he had two divisions, viz., (1) those furnished 

 with palmulae, and (2) those without them. In the former were Ampharete, with fourteen 

 bristled segments and ciliated tentacles, Lysippe, with sixteen tufts of bristles and smooth 

 tentacles, Amphicteis, with seventeen bristle-tufts, and Sosane, with fifteen bristle-tufts, 

 both with smooth tentacles. Of those devoid of palmulae Sabellides had fourteen bristle- 

 tufts, ciliated tentacles and four branchiae, Amage fourteen bristle-tufts, smooth tentacles 

 and four branchiae, Samytha seventeen bristle-tufts, smooth tentacles and three branchiae. 

 Lastly, in the second great group the segments of the body are about seventy in number 

 and the frontal lobe is absent. The single genus Melinna had eighteen bristle-tufts, 

 smooth tentacles and four branchiae. The species are on the whole northern, abounding, 

 for instance, in the Gulf of St. Lawrence, Canada, and in the Arctic Seas. 



