GLOSSOBALANUS MARGINATUS 591 



necessary at that period to prevent the escape of the sperms 

 while the creature occupies the burrow. But even so it 

 must be acknowledged that the marginal outgrowth is 

 a morphological feature, and this has been indicated in the 

 specific name chosen for the species, which is further charac- 

 terized by (1) the brown pigment cells and their concentration 

 into a double series of ventral pigment spots ; (2) the asym- 

 metrical condition of the body, the blind sac, and the 

 genital wings ; (3) the large size of the genital wings ; (4) the 

 short third branch of the gonad. The depth at which 

 the specimen was obtained, 52 fathoms or 95 metres, may 

 also be a peculiarity. 



2. The Larva. 



The adult is not common and probably occurs in isolated 

 communities, one of which lies off the coast of Northumber- 

 land. An enteropneustan larva has been got rarely in the 

 North Sea, and it is worth while inquiring whether it is 

 likely related to Glossobalanus. 



On August 6, 1890, a Tornaria was captured at the surface 

 in St. Andrews Bay, and I made a drawing of it in the living 

 condition in the Marine Laboratory there. This drawing 

 I reproduce (Text-fig. 14). It will be seen to be very like 

 a figure published by Bourne (1890) of a Tornaria captured 

 over deep water in the Channel. His figure 13 and the one 

 I now give are so similar as to lead to the opinion that they 

 belong not merely to the same genus but to the same species. 

 The anterior region is broad, the apical plate somewhat dorsal 

 to the mid-longitudinal line and occupied by a pair of optic 

 pits, the pre-oral and post-oral ciliated bands are simple not 

 presenting lateral folds or processes, there is a slight charac- 

 teristic bending of the transverse part of the post-oral band, 

 the stomach and intestine are wide. A Tornaria of this type, 

 and agreeing completely with the St. Andrews example, was 

 captured on July 27, 1921, off the Longstone, during a 

 plankton trip of the Evadne, in the mid-water net. Bourne 

 regarded his specimen as a fully-developed larva. A similar 



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