222 



Otf GEPHYKEANS OE THE MEEGTJI ARCHIPELAGO. 



muscles of the body by subdivision, for each is inserted in front to 

 the same body-muscle as that from which it originates further back. 

 There is no regularity of arrangement in these accessory muscles ; 

 in some their hinder insertion extends back to the hinder third 

 of the body ; in others, only just beyond the insertion of the 

 retractors of the introvert ; but the majority originate just before, 

 or beyond, the middle of the body. Their insertion is equally 

 variable, as 3 or 4 are inserted at the base of the retractors, and 

 perhaps a single one about the middle of the retractor, while 

 others extend, to the body-wall from 5-8 centim. beyond the 

 sclerorhynchus ; but one or two extend as far forward as the 

 sclerorhynchus. In general the dorsal accessory muscles have a 

 greater length, and extend further back than the ventral muscles. 

 Sometimes two adjacent longitudinal muscles each throw oft' one 

 accessory muscle; then follow several undivided longitudinal 

 muscles in succession. The tendency to such subdivision of the 

 longitudinal body-muscles, however, exhibits itself at several other 

 points, as, for instance, when an accessory muscle rises from the 

 longitudinal muscle only to reunite with it one or a few centims. 

 further on. 



Only a portion of the intestinal canal was in good preservation — 

 the oesophagus, the spiral at the end of the body, and the rectum. 

 Two contractile sacs were visible on the oesophagus, without 

 constrictions ; the intestinal coil was not fixed at the hinder end 

 of the body, but free, and consisted here of a double spiral, the 

 convolutions of which were fixed further forward by many delicate 

 fibres to the body-wall. The rectum was attached to the inner 

 body-wall by a mesentery for a length of 5 centim. ; the anus is 

 placed unusually far forward, being only 5 millim. beyond the 

 sclerorhynchus. Where the rectum separates from the body- wall 

 and the intestinal coil passes into it, the slightly developed spindle- 

 muscle also arises. 



I can give no positive information respecting the ncphridia, as 

 they were macerated. In one of the two specimens I thought I 

 recognized two fragments of ncphridia ; thoir external openings 

 appeared to lie a little in front of the four retractors of the intro- 

 vert ; but I am not positive on this point. 



Among the other Gophyroa sent to me for examination I found 

 a pecimen of a Bonellia ; but unfortunately so imperfect that I 

 was not in a position to determine the species. 



