584 ALEXANDER MEEK 



prol)oscis porp, all lead to the impression that the specimen 

 belongs to the family Ptychoderidae. This family includes 

 the genera Ptychodera, Balanoglossus, and (ilossobalanus, 

 and it has already been seen that the specimen bears some 

 undoubted claims to affinity with Glossobalanus. 



Now there is no better region of the body which may be 

 appealed to for the purpose of setthng which genus is the right 

 one than the post-branchial region. In Ptychodera the gills 

 open by wide lateral slits, in the others by small pores. In 

 Ptychodera the gonads open by many openings on the inner 

 aspect of the genital wings, in Balanoglossus by a single 

 series of pores near to the gill-pores, in (ilossobalanus by 

 a single series of pores on or near the margin of the genital 

 wings. 



I felt justified, therefore, in excising and cutting into 

 sections a small part of this region. Unfortunately the 

 specimen was indifferently preserved, and had to be subjected 

 to several changes of alcohol. Good sections were therefore 

 not to be expected and they were not obtained. The internal 

 epithelium suffered most, as ISpengel found in the case of 

 Glossobalanus elongatus. But the general morpho- 

 logical features were quite well displaj-ed, and in the case of 

 the gonads in particular even histological detail. 



Before proceeding to describe the more important features 

 displayed by the sections it is obvious that the presence of 

 synapticula shows that we were right with regard to family, 

 and the opening of the gonads near the margin and the disposi- 

 tion of the lateral septum indicate that the genus to which 

 the specimen belongs is Glossobalanus. The specimen agrees 

 also with the majority of the species in possessing a com- 

 paratively short branchial region. 



Post-branchial Kegion. — A portion of about 6 mm. 

 of this region was removed and cut into transverse sections 

 and Text-figs. 7-11 are from shdes 1, 11, 19, 22, 23, and 24. 

 Text-fig. 12 is taken from shde 16, and Text-fig. 13 from slide 

 4. The sections show that in spite of the large genital wings 

 the specimen is structurally a Glossobalanus. The asym- 



