GLOSSOBALANUS MARGINATUS 593 



are two types of larvae, one of which is more than hkely 

 the larva of Balanoglossus clavigerus, and the 

 other somewhat but not widely different. There are also 

 found on the south side of the same region two nearlj^ related 

 genera, Balanoglossus and Glossobalanus, the latter with 

 the species G. minutus and G. sarniensis. It is 

 possible that the second type of larva is connected with 

 Glossobalanus, and if the evidence be extremely slender it 

 gains a little in weight by the fact that the same type of 

 larva and adult are present in the North Sea. Bourne's 

 larva may thus be related to either G. minutus or to 

 G. sarniensis, or it may refer to a species which is not 

 obtained inshore but at some depth and not yet discovered. 



The North Sea type of larva is not unlike that described 

 by Agassiz and by Morgan from the Atlantic coast of the 

 North Atlantic, and a similar larva also occurs on the coast 

 of Cahfornia (Eitter and Davis, 1904). 



Summary. 



The specimen de.scribed was captured off the Northumber- 

 land coast on August 22, 1921, and its discovery extends 

 the range of the Enteropneusta to the North Sea and to the 

 east coast of the British Isles. It also adds a new genus to 

 the British list. It belongs to the family Ptychoderidae and 

 to the genus Glossobalanus, but it presents features which 

 indicate that it is a new species which has been called 

 Glossobalanus marginatus. It has been suggested 

 that it may be related to a larva which has also been found 

 in the North Sea. 



It is a pleasure to express grateful thanks to Sir S. F. 

 Harmer and Mr. Kirkpatrick of the British Museum of 

 Natural History — to the former for valuable guidance in 

 literature, and to the latter for an opportunity of examining 

 the museum's collections of Enteropneusta. 



