62 AMPHARETID^E. 



line), whilst the ventral longitudinal muscles are separated by a considerable interval in 

 which the nerve-cords lie, each having a neural canal at the inner edge. The oblique 

 muscles extend from the foot to the upper part of the cords, fibres apparently passing over 

 them as well as joining the circular coat. 



In the posterior region, again, the dorsal longitudinal muscles are thicker and still 

 fused in the mid-dorsal line and the subjacent circular coat is thicker. The oblique 

 muscles are short and powerful, as in the Opheliidae, cutting off, as it were, the 

 ventrolateral projections, but apparently the chief factor is the circular coat— if these 

 sketches are accurate. In the projecting areas are the ventral longitudinal muscles, which 

 are circular in section, but as the author shows another muscular area at the extreme end 

 there is doubt. 



The nerve-cords lie beneath the transverse fibres, apparently from the circular coat, 

 the oblique fibres touching their sheath laterally. A single neural canal now lies between 

 them (Fauvel). In this group, as in the Amphictenida3, the tentacular membrane is 

 absent, the organ being represented by a raised band behind the tentacles, which are 

 supplied by small nerves from the anterior part of the cephalic ganglia. Nuchal organ, 

 as in the Amphictenidae, raised posteriorly. The cephalic nerves are larger and more 

 distinct than in the Amphictenida3, probably because the region is more glandular. The 

 representative of the tentacle-membrane is divided by two longitudinal grooves into 

 three parts. The nerve supplies the mid-region and the inner parts of the two 

 outer (Hessle). 



The alimentary canal in Ampharete Grubei presents mouth, pharynx, oesophagus, 

 stomach, with two reddish or orange diverticula in front, the rest being greenish 

 brown, and followed by the intestine. In most of the family these sacs occur, and 

 in some the oesophagus has two lobes. Wiren 1 has described and figured the blind 

 sacs in Amphicteis Gumieri and Melinna cristata, whilst Fauvel has clone so in Ampharete 

 Grubei? 



In connection with the circulation of the greenish blood, the dorsal trunk terminates 

 anteriorly in four main branches to the branchiae, each of which has an afferent and an 

 efferent trunk as well as a nerve, whilst the gut is surrounded by a sinus. The " heart " 

 extends from the third to the eighth segment and has a cardiac body. The ventral 

 trunk stretches from the posterior to the anterior end and carries the blood from front to 

 rear. Its branches are the bifid " clypeal " in the abdominal region and twigs to the feet 

 throughout. Other trunks are the lateral anastomotic connecting the branches to the feet 

 (Fauvel). 



The branchiae in the genus Isolda of this group are interesting since the outer are 

 thread-like, whilst the inner have lateral processes, making them feather-like. 



Hessle (1917) observes that the nephridia of the fourth segment have long tubes, the 

 rest have short, and that the nephridiopores in the fourth segment open dorsally in certain 

 forms — behind or between the branchia. 



Two pairs of segmental organs occur in Ampharete Grubei (Fig. 144). The anterior pair, 

 are of considerable length, but present the structure of a folded tube with two apertures, 



1 ' Kongl. Sv. Yet. Handl./ Bd. xxi, No. 7. 



2 ' Ball, scientif. France et Belgique/ t. xxx. 



