GLOSSOBALANUS MARGINATUS 583 



are formed by the folds ending in succession along the same 

 line. Posteriorly the lateral walls are occupied by grooves 

 and folds which pass in this manner from the ventral aspect 

 upwards and backwards. The condition ventrally of the 

 folds is remarkably similar to that described by Spengel 

 in the case of Glossobalanus elongatus from the 

 Gulf of Naples. The only difference is that in the North 

 Sea specimen the folds are fairly regular in size, whereas in 

 the Naples form they were alternately large and small. 

 Spengel pointed out with regard to them : ' Mir ist eine 

 solche Anordnung, die sicher bei Gl. sarniensis nicht 

 vorkommt, bis jetzt von keiner Enteropneustenform 

 bekannt.' It may be remarked that the Naples specimen 

 is asymmetrical much as the North Sea one is asymmetrical. 



The right series of gonads end slightly in front of the 

 left and give place to the liver caeca in the form of diver- 

 ticula of the gut and the body-wall on either side of the 

 mid-dorsal groove which emerges from between the genital 

 wings. At this posterior end of the specimen it is seen that 

 the external folds are paralleled by folds of the wall of the 

 alimentary canal (Text-fig. 4). 



It is impossible from the strongly approximated condition 

 of the genital wings to state the length of the branchial 

 region, and it will be as well here to anticipate the further 

 description and to complete our review of the external 

 characters by saying that it is about 15 mm. This region is 

 covered externally by the large genital wings so that the 

 usual triangular space behind the collar is reduced to a slit 

 and even basally next the collar the space is not very wide 

 (Text-fig. 1). It is further to be observed, not merely 

 by the presence of a groove which delimits the genital 

 \vings from the ventral body-wall of this front region of the 

 trunk, that the branchial region is defined from a widely 

 expanded oesophageal region. 



These features, the distinct oesophageal chamber below the 

 branchial region, the absence of a vermiform process to the 

 diverticulum, the presence of liver caeca, the single median 



