GLOSSOBALANUS MARGINATUS 587 



is certainly an interruption, along the line, that is to say, 

 which Spengel defines as the sub-median line. 



The genital wings are large and bend over the dorsal part 

 of the body to arch over a spacious atrial cavity. The 

 gonads occupy the wings and are resolved each into outer and 

 inner lobes, both much folded, but they amalgamate near the 

 summit of the wing to open by a pore not at the margin but 

 near it on the inner face of the wing. The margin of the 

 wing beyond the series of gonopores is a thin flap which is 

 reflected or may be reflected over the openings and serves 

 to occlude that part of the atrial cavity. The outer lobe of 

 the gonad is continued into this margin so that a short third 

 branch is present. In this respect the specimen indicates 

 an approach to the condition of Balanoglossus, and is 

 distinct from all the described species of Glossobalanus. An 

 indication of the displacement of the gonopore on the inner 

 side of the genital wing is shown in Spengel's drawing of 

 Glossobalanus minutus. 



In the anterior end of the branchial region it is evident 

 that the gill-pores and the gonopores come into closer 

 relationship, but with the expansion of the genital wings 

 they are carried apart reaching the condition figured. An 

 inspection of the specimen shows, moreover, that posteriorly, 

 that is to say behind the branchial region, the gonopores 

 still occupy a high position on the wings. Several authors 

 have attempted to show that a relationship exists seg- 

 mentally between the gonopores and the gill-pores, and in this 

 specimen this appears to be the fact, for the succession of the 

 gill-pores is accompanied by a succession of gonopores. In 

 other words the region cut into sections bears the same number 

 of each. There are about five gonopores to 2 mm. in the 

 post-branchial region, and if the same distance between them 

 is retained over the length of the genital region there ought 

 to be some 120 pairs of gonads and gonopores. 



The outer and inner lobes of the gonad are separated by 

 a lateral septum which extends from the region of the line 

 of the gonopores to the dorsal genital groove, and it is 



