GLOSSOBALANUS MARGINATUS 589 



balanus eloiigatus (1904). The septum is a double one 

 and transmits the lateral vessels to the wing. It is also 

 connected by strands to both the inner and outer walls of 

 the wnigs and here also the pigment cells occur The 

 pigment cells are found also under the muscles of the dorsal 

 wall of the body, between the oesophageal region of the 

 alimentary canal and the muscles of the ventral body-wall 

 and on either side the pigment expands into conspicuous 

 masses which rise and fall with the folds of the body-wall as 

 has been noted. 



In the above respects the specimen is very hke other species 

 of Glossobalanus. There is a close resemblance also with 

 reference to another feature, with at the same time a dis- 

 tinction of importance and morphological interest (Text-figs 

 8-11). At the posterior end of the branchial region the gills 

 become short and relegated to the dorsal side of the region 

 Ihe shortening of the gills is accompanied by a gain of the 

 narrow part of the ahmentary canal intervening between the 

 pharynx and the oesophagus. As soon as the gills end this 

 upper part of the tube suddenly expands dorsally and projects 

 as a short diverticulum over the posterior gills of the right 

 side, and in this region the dorsal mesentery is lengthened 

 on the inner side of the diverticulum. The other species of 

 Glossobalanus, as Spengel has shown, present such a diverti- 

 culum, but m all evidently it is a median one, or nearly so 

 m fi-ont of which a similar lengthening of the dorsal mesentery 

 has been remarked. The condition of the North Sea specimen 

 IS therefore like that of the others,, but it differs in the out- 

 growth being asymmetrical. It is scarcely necessary to say 

 hat the blmd sac recalls in its position and its origin the 

 hepatic diverticulum of Amphioxus. 



The North Sea specimen is a male in the act of spawning. 

 Most of the gonads in the region of the sections are empty 

 or nearly so, and the sperms are collected in two masses 

 which occupy the sides of the atrial cavity. The lateral 

 masses are due not only to their issuing from the gonads of 

 each side but to the branchial current which tends to separate 



NO. 264 g g 



